Semi-transmissive-type liquid crystal display device and method for manufacturing same

ABSTRACT

A semi-transmissive-type liquid crystal display device is provided which is capable of preventing an electric erosion reaction between a reflective film made of Al (aluminum) or an Al alloy and a transparent electrode film made of ITO or a like (Indium Tin Oxide) and of inhibiting occurrence of a flicker caused by a residual DC (Direct Current) voltage in the reflective film. In the semi-transmissive-type of a liquid crystal display device, a transmissive region to provide light from a backlight source and a reflective region to receive ambient light are placed in a pixel region and a transparent electrode film is formed above a reflective film formed in the reflective region on an active matrix substrate with a second passivation film being interposed between the reflective film and the transparent electrode film.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a divisional of co-pending U.S. patentapplication Ser. No. 11/408,224, filed on Apr. 20, 2006, which is adivisional of co-pending U.S. patent application Ser. No. 10/615,172,filed on Jul. 8, 2003, which claims the benefit of Japanese PatentApplication No. 2002-201776, filed on Jul. 10, 2002, the entire contentsof each of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semi-transmissive-type liquid crystaldisplay device and a method for manufacturing the same and moreparticularly to the semi-transmissive-type liquid crystal display devicehaving a plurality of pixel regions, each of which has a transmissiveregion and a reflective region and the method for manufacturing thesame.

The present application claims priority of Japanese Patent ApplicationNos. 2002-201776 filed on Jul. 10, 2002, which is hereby incorporated byreference.

2. Description of the Related Art

A liquid crystal display device, thanks to its features being compact,thin, and low-power consuming, is becoming commercially practical inwide applications such as OA (Office Automation) equipment, portablecellular phones, or a like. Two types of methods for driving liquidcrystal display devices including an active matrix method and a passivematrix method are known and the former that enables high quality displayin particular is widely used. Moreover, such the liquid crystal displaydevice that can be driven by the active matrix method is furtherclassified into two types of the liquid crystal display devices, onebeing a transmissive-type liquid crystal display device and anotherbeing a reflective-type liquid crystal display device and both thetwo-types of liquid crystal display devices are operated based on aprinciple that a liquid crystal panel making up a main component of theliquid crystal display device serves as an electronic shutter to pass orintercept light fed from an outside to display an image and, therefore,the both have no self-emitting function, unlike in the case of a CRT(Cathode Ray Tube) display device, an EL (Electroluminescence) displaydevice or a like. As a result, a liquid crystal display of any typeseparately requires a light source in order to display an image. Forexample, a transmissive-type liquid crystal display device isconstructed so as to have a light source made up of a backlight sourceon a rear (that is, on a face opposite to an image display face) of theliquid crystal panel and so that a liquid crystal panel does switchingbetween transmission and interception of light fed from the backlightsource to control the display.

In such the transmissive-type liquid crystal display device as describedabove, a bright image can be obtained by receiving light fed from abacklight source all the time, irrespective of ambient brightness inplaces where the transmissive-type liquid crystal display device isused, however, its power consumption of the backlight source isgenerally large and a half of power of the transmissive-type liquidcrystal display device is consumed by the backlight source, thus causingan increase in its power consumption. Especially, in the case of atransmissive-type liquid crystal display device that is driven by abattery, time during which the liquid crystal display can be used isshort and, if a large-sized battery is employed in order to lengthen thetime during which the liquid crystal display can be used, weight of anentire liquid crystal display device become large, causing an obstacleto making the device compact and lightweight.

To solve the problem of power consumption by a backlight source in atransmissive-type liquid crystal display device, a reflective-typeliquid crystal display device is proposed which is constructed so thatuse of a light source is made unnecessary and light (ambient light)existing in a place surrounding the liquid crystal display device isused as a light source. The reflective-type liquid crystal displaydevice is constructed so that a reflective plate is placed within aliquid crystal panel and displaying of an image is controlled in amanner that switching is done between transmission and interception ofambient light which has been fed into an internal portion of the liquidcrystal panel and has been reflected off the reflective plate.

In the reflective-type liquid crystal display device, unlike in the caseof the transmissive-type liquid crystal display device, since light fromthe backlight source is not required, it is possible to reduce its powerconsumption, to make it small-sized and lightweight. However, such thereflective-type liquid crystal display device has a problem in that, ifit is dark in surroundings, ambient light does not serve sufficiently asa light source and therefore visibility is remarkably lowered.

Thus, each of a transmissive-type liquid crystal display device and areflective-type liquid crystal display device has both merits anddemerits. In order to obtain stable display, though light fed from abacklight source is effective, if only a backlight source is used as alight source, an increase in power consumption is inevitable.

To solve this problem, a conventional semi-transmissive-type liquidcrystal display device is proposed, which is constructed so as to haveboth a transmissive region and a reflective region in a pixel region ofa liquid crystal panel in order to reduce power consumption of abacklight source and to improve visibility even in the case of darkambient light and so that operations as a transmissive-type liquidcrystal display device and as a reflective-type liquid crystal displaydevice can be performed by one liquid crystal panel.

Since such the semi-transmissive-type liquid crystal display device asdescribed above has both the transmissive region and reflective regionin the pixel region of the liquid crystal panel, even when ambient lightis dark, by turning ON a backlight source and by using the abovetransmissive region, the semi-transmissive-type liquid crystal displaydevice can be operated as the transmissive-type liquid crystal displaydevice and a characteristic of high visibility that thetransmissive-type liquid crystal display device provides can be fullyutilized. On the other hand, when ambient light is fully bright, byturning OFF the backlight source and by using the above reflectiveregion, the conventional semi-transmissive-type liquid crystal displaydevice can be operated as the reflective-type liquid crystal displaydevice and a characteristic of low power consumption that thereflective-type liquid crystal display device provides can be fullyutilized.

In the conventional semi-transmissive-type liquid crystal device, lightfed from a backlight source passes through a liquid crystal layer in thetransmissive region used to have the conventional semi-transmissive-typeliquid crystal device be operated as the transmissive-type liquidcrystal display device and, on the other hand, incident light beingambient light travels and returns through the liquid crystal layer inthe reflective-type liquid crystal display device used to have theconventional semi-transmissive-type liquid crystal display device beoperated as the reflective-type liquid crystal display and, as a result,a difference in optical paths occurs between the incident light fed fromthe backlight source and the light being ambient light in the liquidcrystal layer. Therefore, in the conventional semi-transmisive-typedisplay device, as described later, unless a dimension of a gap(reflective gap) of a reflective region serving as a layer thickness ofa liquid crystal layer and of a gap (transmissive gap) of a transmissiveregion also serving as a layer thickness of the liquid crystal layer areset to be optimum values according to a twisted angle of the liquidcrystal layer, intensity of outgoing light output from a display surfacecannot be made optimum, due to a difference in retardation in thereflective region and in the transmissive region. Optimization ofintensity of outgoing light in a transmissive region and a reflectiveregion of a pixel region in the conventional semi-transmissive-typeliquid crystal display device is described below.

[1] Optimization of Intensity of Outgoing Light in Transmissive Regionand Reflective Region

FIG. 34 is a diagram showing an outline of configurations of aconventional semi-transmissive-type liquid crystal display device neededto optimize intensity of outgoing light in a transmissive region and ina reflective region. The conventional semi-transmissive-type liquidcrystal display device, as shown in FIG. 34, includes an active matrixsubstrate 112, a facing substrate 116, a liquid crystal layer 117 beingsandwiched between both the active matrix substrate 112 and the facingsubstrate 116, a backlight 118 being placed on a rear of the activematrix substrate 112, phase difference plates (λ/4, 4 plates) 120 a and120 b being placed on an outside of each of the active matrix substrate112 and the facing substrate 116, and polarizers 119 a and 119 b. Here,on a surface of the active matrix substrate 112 being opposite to thefacing substrate 116 are placed a transmissive film 105 serving as atransmissive region in a pixel region and a reflective film 106 servingas a reflective region in the pixel region. Thus, by constructing theconventional semi-transmissive-type liquid crystal display device byarranging each of the components, it is made possible to control a stateof polarization of incident light and outgoing light, as describedlater.

[2] Arrangement of Polarizer and Phase Difference Plate Placed in UpperPosition

First, a case is explained in which the above conventionalsemi-transmissive-type liquid crystal display device is operated as areflective-type liquid crystal device. A phase difference plate 120 b isplaced between the liquid crystal layer 117 and the polarizer 119 b sothat the reflective region is displayed in a normally white mode, thatis, white display is made by a state in which liquid crystal moleculesof the liquid crystal layer 117 lay themselves down (that is, liquidcrystal molecules lie in a horizontal direction) due to no applicationof voltages between a facing electrode (not shown) of the facingsubstrate 116 and a pixel electrode (not shown) of the active matrixsubstrate 112 and so that black display is made by a state in whichliquid crystal molecules stand up (that is, the liquid crystal moleculesrise in a vertical direction) due to application of voltages between thefacing electrode (not shown) of the facing substrate 116 and the pixelelectrode (not shown) of the active matrix substrate 112. By placing thephase difference plate 120 b in an manner so as to be rotated by 45°relative to an optical axis of the polarizer 119 b, linearly polarizedlight (horizontal light) being ambient light having passed through thepolarizer 119 b becomes clockwise circularly polarized light. Theclockwise circularly polarized light reaches the reflective light 106 asa linearly polarized light by setting a reflection gap “dr” at aspecified value. The linearly polarized light is reflected off thereflective film 106, as it is, as linearly polarized light and becomesclockwise circularly polarized light when going out from the liquidcrystal layer 117. The clockwise circularly polarized light is changedto be a linearly polarized light (horizontal light) by the phasedifference plate 120 b and goes out through the polarizer 119 b havingan optical axis in a horizontal direction and is displayed in a whitemode. On the other hand, when a voltage is applied between the abovefacing electrode (not shown) and the above pixel electrode (not shown),liquid crystal molecules rise. At this point, light having incident onthe liquid crystal layer 117 as clockwise circularly polarized lightreaches the reflective film 106 as it is and is changed to becounterclockwise circularly polarized light by the reflective film 106and is then reflected. The counterclockwise circularly polarized light,after having been emitted from the liquid crystal layer 117, is changedto be linearly polarized light (vertical light) by the phase differenceplate 120 b and is absorbed by the polarizer 120 b without beingemitted. This causes black display to be made.

[3] Arrangement of Polarizer and Phase Difference Plate Placed in LowerPosition

Next, a case is explained in which the above conventionalsemi-transmissive-type liquid crystal display device is operated as atransmissive-type liquid crystal display device. Arrangement angle of anoptical axis of each of the phase difference plate 120 a and thepolarizer 119 a both being placed in a lower position is determined sothat black display is made with a voltage being applied. The polarizer119 a in the lower position and the polarizer 119 b in the upperposition are placed in a manner so as to produce a cross Nicolrelationship, that is, in a manner that the polarizer 119 a in the lowerposition is arranged in a direction being rotated by 90° relative to thepolarizer 119 b. Moreover, in order to cancel (or compensate for) aninfluence by the phase difference plate 120 b placed in the upperposition, the phase difference plate 120 a is placed in a manner thatthe phase difference plate 120 a placed in the lower position is rotatedalso by 90° relative to the phase difference plate 120 b placed in theupper position. Since liquid crystal molecules have risen while avoltage is being applied, a state of polarization of light remainsunchanged. That is, a state in which liquid crystal molecules have risenwith a voltage being applied is optically equivalent to a state in whichthe polarizer 119 a and the polarizer 119 b are placed in a manner so asto produce a cross Nicol relationship between them, thus causing blackdisplay to be made with a voltage being applied. By configuring asabove, arrangement of optical components and arrangement angle of anoptical axis are determined in a liquid crystal panel in theconventional semi-transmissive-type liquid crystal display device.

[4] Setting of Twisted Angle

FIG. 35 shows a relation among a twisted angle (0° to 90°) of a liquidcrystal, a reflection gap “dr” (layer thickness of a liquid crystallayer) and a transmissive gap “df” (layer thickness of a liquid crystallayer) in the conventional semi-transmissive-type liquid crystal displaydevice configured by placing optical components at arrangement anglesdescribed above and by using a nematic liquid crystal havingrefractivity anisotropy “Δn” of 0.086 as the above liquid crystal layer117. Moreover, FIG. 36 shows a relation among a twisted angle φ (0° to90°), a transmittance, and a reflectivity obtained when the reflectivegap “dr” and transmissive gap “dr” are optimized in the conventionalsemi-transmissive-type liquid crystal display device. In general, as atwisted angle becomes smaller, a usage rate of light in a transmissivemode becomes the higher and a color shift occurring when a field of viewis swung becomes the larger. As is apparent from FIG. 35, when thetwisted angle φ is about 72°, the reflective gap “dr” and thetransmissive gap “df” are made equal to each other in which areflectivity of white light and a transmittance of white light becomemaximum. Moreover, as the twisted angle φ becomes smaller, the optimumreflective gap “dr” becomes smaller than the optimum transmissive gap“df”.

As is apparent from FIG. 35, the optimum reflective gap “dr” andtransmissive gap “df” are made equal to each other, both being about 2.7μm, when a nematic liquid crystal having refractivity anisotropy Δn of0.086 is used and the twisted angle φ is set at about 72°. When thetwisted angle φ is set at about 0°, a maximum reflective gap “dr” isabout 1.5 μm and a maximum transmissive gap “df” is about 2.9 μm. Whenthe twisted angle φ is set at about 60°, the maximum reflective gap “dr”becomes about 2.0 μm and the maximum transmissive gap “df” becomes about2.8 μm.

As described above, to correct for a difference in optical paths ofincident light passing through the transmissive region and thereflective region in the pixel region and to perform optimization on anintensity of outgoing light in the conventional semi-transmissive-typeliquid crystal display device, it is necessary that an optimumreflective gap “dr” and optimum transmissive gap “df” that maximizesreflectivity and transmittance of white light, depending on a twistedangle of a liquid crystal, have to be set in a manner as shown in FIG.35. Therefore, by placing a step as in the case of the conventionalsemi-transmissive-type liquid crystal display device as shown in FIG. 30so that the reflective gap is made different from the transmissive gapand by forming the active matrix substrate 112 as in the case of theconventional semi-transmissive-type liquid crystal display device asshown in FIG. 33 so that the reflective gap is made equal to thetransmissive gap, a contrivance to obtain an optimum reflective gap andan optimum transmissive gap, depending on a specified twist angle, hasbeen conventionally used.

Configurations of a conventional semi-transmissive-type liquid crystaldisplay device are described below by referring to FIG. 30. Thesemi-transmissive-type liquid crystal display device shown in FIG. 30includes an active matrix substrate 112 on which a TFT (thin filmtransistor) is formed to operate as a switching element, a facingsubstrate 116, a liquid crystal layer 117 being sandwiched between thefacing substrate 116 and the active matrix substrate 112, a backlight118 placed on a rear of the active matrix substrate 112.

The active matrix substrate 112 includes a transparent insulatingsubstrate 108, a gate line and a data line (not shown) being formed onthe transparent insulating substrate 108, a gate electrode 101 aconnected to the gate line, a gate insulating film 109, a semiconductorlayer 103 a, a drain electrode 102 a and a source electrode 102 b drawnfrom both ends of the semiconductor layer 103 a and connectedrespectively to the data line and a pixel electrode (not shown), and apassivation film 110. Also, the pixel region PX is divided into twoportions, one being a transmissive region PXa to allow light fed fromthe backlight 118 to transmit and another being a reflective region PXbto reflect incident ambient light. In the above transmissive region PXa,a transparent electrode film 105 made of ITO (Indium Tin Oxide) or alike being formed on the passivation film 110. In the above reflectiveregion PXb, a reflective electrode film 106 a made of Al (Aluminum) oran Al alloy formed with a concave/convex shaped film 111 made of organicfilms or a like being interposed between the reflective electrode film106 a is formed in a manner to be connected to the transparent electrodefilm 105. The transparent electrode film 105 and the reflectiveelectrode film 106 a being connected to the source electrode 102 bthrough a contact hole 107 formed on the concave/convex shaped film 111operate as a pixel electrode (not shown). On the transparent electrodefilm 105 and the reflective electrode film 106 a is formed an orientatedfilm 129. Here, the TFT 103 is made up of the gate electrode 101 a, gateinsulating film 109, semiconductor layer 103 a, drain electrode 102 and,source electrode 102 b. On the other hand, the facing substrate 116includes a transparent insulating substrate 113, a color filter 114, ablack matrix (not shown), a facing electrode 115, and the orientatedfilm 105.

The semi-transmissive-type liquid crystal display device having such theconfigurations as shown in FIG. 30 operates in a manner that, in thetransmissive region PXa, light from the backlight 118 which has enteredfrom a rear of the active matrix substrate 112, after having passed theliquid crystal layer 117, is output from the facing substrate 116 and,in the reflective region PXb, ambient light which has entered from thefacing substrate 116, after having passed through the liquid crystallayer 117, is reflected off the reflective electrode film 106 a andagain passes through the liquid crystal layer 117 and is then outputfrom the facing substrate 116. By forming a step on the concave/convexshaped film 111 so that the reflective gap “dr” becomes a half of thetransmissive gap “df” (however, in this case, the twisted angle φ is setat about 0°) and by making approximately equal lengths of optical pathsof light passing through each of the transmissive region PXa andreflective region PXb, a polarization state of outgoing light iscalibrated.

A reflective-type liquid crystal display device is disclosed in JapanesePatent Application No. 2001-221995 in which a transparent electrode isformed on a reflective plate having concave/convex portions with aprotective film made of a transparent acrylic resin being interposedbetween the transparent electrode and the reflective plate. In thedisclosed semi-transmissive-type liquid crystal display device, in orderto solve a problem that, if a liquid crystal whose retardation isdifferent between a transmissive display region and a reflective displayregion is oriented at a same driving voltage, a high-contrast displaycannot be obtained and bright display is difficult, orientation of aliquid crystal is controlled after calibration has been made so thatretardation in a portion to perform transmissive display and in aportion to perform reflective display is put into a near range. However,in the disclosed semi-transmissive-type liquid crystal display device, acountermeasure against a display defect caused by an electric erosionreaction and a flicker caused by a residual DC (Direct Current) voltage,which present a problem to be solved in the present invention, is nottaken.

Moreover, in the disclosed semi-transmissive-type liquid crystal displaydevice, since the reflective electrode film (reflective plate) is formedin a central portion of a pixel and a TFT device is not covered by thereflective plate, any countermeasure against problems handled in thepresent invention cannot be taken.

However, such the conventional semi-transmissive-type liquid crystaldisplay device as described above has two problems. One problem (firstproblem) is that, in the conventional semi-transmissive-type liquidcrystal display device, since the reflective electrode film 106 a madeof Al or an Al alloy is formed on the transparent electrode film 105made of ITO, Al and/or ITO are eroded due to an electric erosionreaction when a resist pattern used to perform patterning on thereflective electrode film 106 a is formed. Another problem (secondproblem) is that a flicker occurs due to a residual DC voltage producedin a region of the reflective electrode film 106 a.

The first problem of the electric erosion reaction is described first.For example, in such the conventional semi-transmissive-type liquidcrystal display device as shown in FIG. 30, in order to connect thetransparent electrode film 105 to the source electrode 102 b in the TFT103 through the reflective electrode film 106 a, the transparentelectrode film 105 and the reflective electrode film 106 a are formed soas to overlap each other within each pixel, however, since electricseparation is necessary between pixels adjacent to one another,overlapping between the transparent electrode film 105 in one pixel andthe reflective electrode film 106 a in other pixel being adjacent to theone pixel is not allowed. Therefore, as shown in FIG. 31A, when a resistpattern 121 used to form the reflective electrode film 106 a is formed,only a reflective region side of a conductive film for the reflectiveelectrode film 106 a in each pixel already formed on entire surfaces ofthe pixel region PX has to be covered. However, as shown in FIG. 31B, ifa crack occurs in the reflective electrode film 106 a in an end portion(portion surrounded by broken lines in FIG. 31B) of the transparentelectrode film 105 already formed due to some reasons, a developer 126permeates the reflective electrode film 106 a through this crack 127.

Since the Al material making up the reflective electrode film 106 a ishighly reactive and easily reacts with oxygen, if the developer 126permeates through the crack 127 as described above, the Al materialreacts with ITO being an oxide conductor which makes up the transparentelectrode film 105. As a result, a reaction of erosion (oxidation) of Aland dissolution (reduction) of ITO of the developer 126 serving as anelectrolytic solution, which are called an “electric erosion reaction”)occur which causes a contact failure between the Al and ITO and/or apeeled portion 128 between the poor-adhesive transparent electrode 105and the passivation film 110 occurs. The electric erosion reaction isthought to occur due to a mechanism described below.

-   [A] An Al component having many lattice defect and impurity is    dissolved as a local anode, causing formation of a pinhole.-   [B] The developer 126 comes into contact with ITO contained in a    lower layer through the formed pinhole.-   [C] Oxidation of Al and reduction of ITO given by following    expressions are stimulated by a potential between oxidation    potential of Al and reduction potential of ITO in the developer 126    which serves as a driving force of reaction.

Al+4OH⁻→H₂AlO₃+H₂O+3e  (1)

In₂O₃+3H₂O+6e 2In+6OH⁻  (2)

Although the electric erosion reaction can be suppressed to some extentby taking a layout of the transparent electrode film 105 and thereflective electrode film 106 a, that is, a state of overlapping of ITOand Al, into considerations, the electric erosion reaction is anessential problem in a structure in which an Al film or an Al alloy filmis formed on ITO and, therefore, a proposal of a structure in whichoccurrence of the electric erosion reaction can be surely prevented isexpected.

Next, the second problem of a flicker is explained. Asemi-transmissive-type liquid crystal display device being driven by anactive matrix method is ordinarily operated with an AC (alternatingcurrent) voltage and uses a voltage applied to its facing electrode as areference voltage and feeds a voltage being changed to become a positivepolarity and negative polarity in every period of time to its pixelelectrode (pixel electrode). Though it is preferable that waveforms of apositive voltage applied to a liquid crystal and of a negative voltageapplied to the liquid crystal are symmetric to each other, even if ACvoltages whose waveforms are symmetric are applied to its pixelelectrode, waveforms of the voltage actually applied to the liquidcrystal are not symmetric due to an unintentional DC component asdescribed later. As a result, optic transmittance obtained when apositive voltage is applied is different from that obtained when anegative voltage is applied and luminance changes in a period of an ACvoltage to be applied to a pixel electrode, causing a flicker to occur.As described later, this flicker occurs due to an orientated film 129being formed on a face of each of the facing substrate 116 and activematrix substrate 112 placed on both sides of the liquid crystal layer117 used to control orientation of a liquid crystal molecule.

As a material for the above orientated film 129, a polyimide resin isused because its mechanical strength is sufficient since rubbingprocessing is performed on the thin film with a thickness of aboutseveral hundred angstroms, because the material has a resistance tosolvents to be used in rinsing of the orientated films 129 with water ororganic solvents after rubbing operations have been completed, andbecause the material has a resistance to heat which is generated when anepoxy resin used as a seal material is heated and cured at the time ofsealing of the liquid crystal. However, it is known that the polyimideresin, when rubbing processing is performed thereon or when intenselight is applied thereto, generates an electron within the polyimideresin.

In the semi-transmissive-type liquid crystal display device shown inFIG. 30, on the active matrix substrate 112 are formed the transparentelectrode film 105 and the reflective electrode film 106 a on which (onsurfaces of sides of the liquid crystal layer 117 to be inserted) theorientated film 129 made up of polyimide is applied and, as describedabove, electrons are generated within polyimide due to the rubbingprocessing and/or application of light. Oxidation easily occurs on asurface of Al making up the reflective electrode film 106 a and aSchottky barrier occurs at an interface surface between polyimide andthe Al, making it difficult for electrons within polyimide to go out. Onthe other hand, since ITO making up the transparent electrode film 105is not oxidized, the Schottky barrier does not occur at an interfacesurface between polyimide and ITO, thus allowing electrons depositedwithin polyimide to go out. As a result, electrons reside only inpolyimide making up the orientated film 129 on the reflective electrodefilm 106 a and a residual DC voltage is produced. Since waveforms of aDC voltage to be applied to a pixel electrode (not shown) are notsymmetric to one another due to existence of the DC component, a flickeroccurs.

The second problem is also an essential problem in a structure in which,on an uppermost layer of the active matrix substrate 112 is formed thereflective electrode film 106 a made of Al or a like on which theorientated film 129 made of polyimide is applied and a proposal of astructure in which occurrence of flickers caused by a residual DCvoltage can be prevented is expected.

PREFACE TO THE INVENTION

The occurrence of the electric erosion reaction can be suppressed byimproving a plane layout of the transparent electrode film 105 and thereflective electrode film 106 a and by improving configurations of thereflective electrode film 106 a and the inventors of the presentinvention have made various improvements as shown in FIG. 32 and FIG.33. FIG. 32 is a plan view showing configurations of thesemi-transmissive-type liquid crystal display device proposed by theinventors of the present invention. FIG. 33 is a cross-sectional view ofthe semi-transmissive-type liquid crystal display of FIG. 32 taken alonga line H-H.

An active matrix substrate 112 making up in the semi-transmissive-typeliquid crystal display device, as shown in FIGS. 32 and 33, includes atransparent insulating substrate 108, a gate line 101 and a data line102 formed on the transparent insulating substrate 108, a gate electrode101 a connected to the gate line 101, a gate insulating film 109, asemiconductor layer 103 a, a drain electrode 102 a and a sourceelectrode 102 b being drawn from both ends of the semiconductor layer103 a and being connected respectively to the data line 102 and to apixel electrode (not shown), a passivation film 110, a concave/convexshaped film 111 formed on an entire pixel region PX, a transparentelectrode film 105 formed on the concave/convex shaped film 111 in atransmissive region PXa, and a reflective electrode film 106 a having alayer-stacked structure formed so that the reflective electrode film 106a and all portions surrounding the transparent electrode film 105overlap each other and wherein, as one of means to suppress the electricerosion reaction, a structure is proposed which can calibrate apositional relation on a plane between the transparent electrode film105 and the reflective electrode film 106 a.

That is, the electric erosion reaction, as shown in FIG. 31, is causedmainly by permeation of the developer 126 through a crack 127 havingoccurred in the reflective electrode film 106 a made up of a thin filmat an end of the transparent electrode film 105. To solve this problem,as shown in FIGS. 32 and 33, the permeation of the developer 126 isprevented by having the reflective electrode film 106 a and all portionssurrounding the transparent electrode film 105 overlap with a width of,for example, 2 μm or more to cover all portions surrounding an end ofthe transparent electrode film 105 with a resist pattern 121.

The inventors have devised various methods for preventing permeation ofthe developer 126. That is, since the electric erosion reaction occursdue to permeation of the developer 126 through a pinhole of Al into aninterface surface between Al and ITO, the reflective electrode film 106a is constructed in a manner that metal films made of Al, an Al alloy,or a like are stacked on a barrier metal film made of molybdenum or alike in layers and that each of the metal films is 100 nm or more inthickness to prevent the developer 126 permeating into ITO portions.Moreover, in order to inhibit peeling at an interface surface betweenthe transparent electrode film 105 and the concave/convex shaped film111, by selecting optimum conditions for UV (Ultraviolet) processingand/or oxygen ashing processing on the concave/convex shaped film 111before formation of the transparent electrode film 105, adhesion betweenthe transparent electrode film 105 and the concave/convex shaped film111 is improved to prevent the developer 126 from the permeation.

By employing various configurations and manufacturing methods asdescribed above, it is possible to inhibit electric erosion reactionsoccurring at the time of formation of a resist pattern to be used toperform patterning on the reflective electrode film 106 a. However, evenin such the semi-transmissive-type liquid crystal display device asdescribed above, since the orientated film 129 made of polyimide isformed on the reflective electrode film 106 a, for reasons as describedabove, it is impossible to prevent occurrence of a flicker caused by aresidual DC voltage. The inventor of the present invention studied astructure of a semi-transmissive-type liquid crystal display device thatcan solve the two problems of occurrence of the electric erosionreaction and flickers at a same time and, as a result, has found that itis made possible to simultaneously and effectively solve both the twoproblems by using a semi-transmissive-type liquid crystal display deviceconstructed based on a configuration in which the transparent electrodefilm 105 and reflective electrode film 106 a are stacked in layers in away being reverse to that employed in the conventionalsemi-transmissive-type liquid crystal display device, that is, thereflective electrode film 106 a made of Al or an Al alloy is placed soas to form a lower layer and the transparent electrode film 105 made ofITO is formed directly on the reflective film 106 or with an insulatingfilm being interposed between the reflective electrode film 106 a andthe transparent electrode film 105.

SUMMARY OF THE INVENTION

In view of the above, it is an object of the present invention toprovide a semi-transmissive-type liquid crystal display device beingcapable of preventing an electric erosion reaction between a reflectiveelectrode film (hereinafter, simply called a “reflective film”) and atransparent electrode film and of inhibiting occurrence of a flickercaused by a residual DC voltage in the reflective film and a method formanufacturing the semi-transmissive-type liquid crystal display device.

According to a first aspect of the present invention, there is provideda semi-transmissive-type liquid crystal display device including:

-   -   a first substrate including a plurality of signal electrodes        being arranged in parallel to one another along a first        direction;    -   a second substrate including a plurality of scanning electrodes        being arranged in parallel to one another along a second        direction orthogonal to the first direction and a plurality of        pixel regions each being placed in a one-to-one correspondence        to an intersection between each of the signal electrodes and        each of the scanning electrodes;    -   a liquid crystal layer inserted between the first substrate and        the second substrate;    -   a backlight source to feed light to the liquid crystal layer;        and    -   wherein each of the pixel regions includes a reflective region        having a reflective film to receive ambient light from an        outside and to display in a reflective manner while being in a        reflective display mode, and a transmissive region having a        transmissive electrode film to allow light from the backlight        source to be transmitted to display in a transmissive manner at        time of operations in a transmissive display mode; and    -   wherein in each of the pixel regions, the transparent electrode        film is extended to the reflective film in a manner to cover at        least one part of the reflective film.

In the foregoing first aspect, a preferable mode is one wherein thetransparent electrode film is formed over the reflective film through aninsulating film which is interposed between the transparent electrodefilm and the reflective film.

Another preferable mode is one wherein the transparent electrode film isformed directly on the reflective film.

Still another preferable mode is one wherein the reflective film iselectrically connected to the transparent electrode film through acontact hole formed in the insulating film.

An additional preferable mode is one wherein in each of the pixelregions, a switching element to turn on or off a voltage signal to beapplied to the liquid crystal layer is formed on a surface of the firstsubstrate at a side facing the second substrate and the reflective filmis formed in a manner to cover the switching element.

A still additional preferable mode is one wherein the reflective filmcovers the switching element with an insulating film having a concaveand convex surface being interposed between the reflective film and theswitching element.

A furthermore preferable mode is one wherein a contact hole is formed ina manner so as to contact commonly with the insulating film and, in thecontact hole, the reflective film and the transparent electrode film areelectrically connected to an arbitrary electrode out of a plurality ofelectrodes making up the switching element.

A still furthermore preferable mode is one wherein a first contact holeand a second contact hole are formed in the insulating film and thereflective film is electrically connected to one electrode of theswitching element through the first contact hole and the transparentelectrode film is electrically connected to one electrode of theswitching element through the second contact hole.

Also, a furthermore preferable mode is one wherein a G-D (Gate-Drain)converting portion to draw a signal line used to apply a voltage signalto the liquid crystal layer from a gate layer on the surface of thefirst substrate at the side of facing the second substrate outside ofthe transmissive region and the reflective region.

Also, a still furthermore preferable mode is one wherein the reflectivefilm is made of a conductive material containing Al (aluminum) or an Alalloy and the transparent electrode film is made of ITO (Indium TinOxide).

According to a second aspect of the present invention, there is provideda semi-transmissive-type liquid crystal display device including:

-   -   a first substrate including a plurality of signal electrodes        being arranged in parallel to one another along a first        direction;    -   a second substrate including a plurality of scanning electrodes        being arranged in parallel to one another along a second        direction orthogonal to the first direction and a plurality of        pixel regions each being placed in a one-to-one correspondence        to an intersection between each of the signal electrodes and        each of the scanning electrodes;    -   a liquid crystal layer inserted between the first substrate and        the second substrate;    -   a backlight source to feed light to the liquid crystal layer;        and    -   wherein each of the pixel regions includes a reflective region        having a reflective film to receive ambient light from an        outside and to display in a reflective manner while being in a        reflective display mode, and a transmissive region having a        transmissive electrode film to allow light from the backlight        source to be transmitted to display in a transmissive manner at        time of operations in a transmissive display mode; and    -   wherein in each of the pixel regions, a first gap between the        first substrate and the second substrate in the reflective        region and a second gap between the first substrate and the        second substrate in the transmissive region are calibrated so        that reflectance or transmittance in white display is maximized        according to a twisted angle of the liquid crystal layer.

In the foregoing second aspect, a preferable mode is one wherein, when atwisted angle of the liquid crystal is set to about 72°, a calibrationis so done that the first gap in the reflective region becomes equalapproximately to the second gap in the transmissive region.

Another preferable mode is one wherein, when a twisted angle of theliquid crystal is set to about 0°, a calibration is so done that thefirst gap in the reflective region is approximately a half of the secondgap in the transmissive region.

Still another preferable mode is one wherein, when a twisted angle ofthe liquid crystal is set to about 60°, a calibration is so done thatthe first gap in the reflective region accounts for approximately 70% ofthe second gap in the transmissive region.

According to a third aspect of the present invention, there is provideda method for manufacturing a semi-transmissive-type liquid crystaldisplay device including a first substrate including a plurality ofsignal electrodes being arranged in parallel to one another along afirst direction; a second substrate including a plurality of scanningelectrodes being arranged in parallel to one another along a seconddirection orthogonal to the first direction and a plurality of pixelregions each being placed in a one-to-one correspondence to anintersection between each of the signal electrodes and each of thescanning electrodes; a liquid crystal layer inserted between the firstsubstrate and the second substrate; a backlight source to feed light tothe liquid crystal layer; and wherein each of the pixel regions includesa reflective region having a reflective film to receive ambient lightfrom an outside and to display in a reflective manner while being in areflective display mode, and a transmissive region having a transmissiveelectrode film to allow light from the backlight source to betransmitted to display in a transmissive manner at time of operations ina transmissive display mode, the method including:

-   -   a first process of forming the reflective film making up the        reflective region on a surface of the first substrate facing the        second substrate; and    -   a second process of forming the transparent electrode film        making up the transmissive region in a manner that the        transparent electrode film covers part or all of the reflective        film.

In the foregoing third aspect, a preferable mode is one that whereinfurther includes including a third process of forming an insulating filmon the reflective film to be performed between the first process and thesecond process.

Another preferable mode is one that wherein further includes a fourthprocess of forming a contact hole to electrically connect the reflectivefilm and the transparent electrode film in the insulating film.

According to a fourth aspect of the present invention, there is provideda method for manufacturing a semi-transmissive-type liquid crystaldisplay device including a first substrate including a plurality ofsignal electrodes being arranged in parallel to one another along afirst direction; a second substrate including a plurality of scanningelectrodes being arranged in parallel to one another along a seconddirection orthogonal to the first direction and a plurality of pixelregions each being placed in a one-to-one correspondence to anintersection between each of the signal electrodes and each of thescanning electrodes; a liquid crystal layer inserted between the firstsubstrate and the second substrate; a backlight source to feed light tothe liquid crystal layer; and wherein each of the pixel regions includesa reflective region having a reflective film to receive ambient lightfrom an outside and to display in a reflective manner while being in areflective display mode, and a transmissive region having a transmissiveelectrode film to allow light from the backlight source to betransmitted to display in a transmissive manner at time of operations ina transmissive display mode, the method including:

-   -   a process of performing a calibration on a first gap between the        first substrate and the second substrate in the reflective        region and a second gap between the first substrate and the        second substrate in the transmissive region so that reflectance        or transmittance in white display is maximized according to a        twisted angle of the liquid crystal layer by inserting the        liquid crystal layer between the first substrate and the second        substrate,    -   wherein the first substrate is formed by processes of forming        the reflective film making up the reflective region on a surface        of the first substrate facing the second substrate and of        forming the transparent electrode film making up the        transmissive region in a manner that the transparent electrode        film covers part or all of the reflective film.

In the foregoing fourth aspect, a preferable mode is one wherein acalibration is performed on the first gap between the first substrateand the second substrate in the reflective region and the second gapbetween the first substrate and the second substrate in the transmissiveregion so that reflectance or transmittance in white display ismaximized according to a twisted angle of the liquid crystal layer byforming the reflective film on a surface of the first substrate facingthe second substrate through an insulating film having a concave andconvex surface being interposed between the reflective film and thesecond substrate.

Another preferable mode is one wherein a calibration is performed on thefirst gap between the first substrate and the second substrate in thereflective region and the second gap between the first substrate and thesecond substrate in the transmissive region so that reflectance ortransmittance in white display is maximized according to a twisted angleof the liquid crystal layer by processing a surface of the firstsubstrate facing the second substrate.

Also, a furthermore preferable mode is one wherein a thickness of theinsulating film is made different between the transmissive region andthe reflective region.

With the above configurations, by inserting a liquid crystal layerbetween a first substrate and a second substrate, constructing a pixelregion of the liquid crystal layer, and placing a transmissive region toprovide light from a backlight and a reflective region to receiveambient light in the pixel region, having a transparent electrode filmextend in each pixel to the reflective region in a manner so as to coverpart or all of the reflective film, an electric erosion reaction betweenthe reflective region and the transparent electrode film can beprevented and a flicker caused by a residual DC voltage of thereflective film can be suppressed.

With another configuration as above, by inserting a liquid crystal layerbetween a first substrate and a second substrate, constructing a pixelregion of the liquid crystal layer, placing a transmissive region toprovide light from a backlight and a reflective region to receiveambient light, and forming, after having formed the reflective film, thetransparent electrode film in a manner so as to cover part or all of thereflective film, an electric erosion reaction between the reflectiveregion and the transparent electrode film can be prevented and a flickercaused by a residual DC voltage of the reflective film can besuppressed.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, advantages, and features of the presentinvention will be more apparent from the following description taken inconjunction with the accompanying drawings in which:

FIG. 1 is a plan view for showing a configuration of asemi-transmissive-type liquid crystal display device according to afirst embodiment of the present invention;

FIG. 2 is a cross-sectional view for showing a configuration of thesemi-transmissive-type liquid crystal display device of FIG. 1 takenalong a line A-A.

FIGS. 3A, 3B, and 3C are process charts illustrating a manufacturingmethod of an active matrix substrate making up thesemi-transmissive-type liquid crystal display device in order of stepaccording to the first embodiment of the present invention;

FIGS. 4A and 4B are also process charts for illustrating themanufacturing method of the active matrix substrate making up thesemi-transmissive-type liquid crystal display device in order of stepaccording to the first embodiment of the present invention;

FIG. 5 is a cross-sectional view for showing an other configuration ofan active matrix substrate of the semi-transmissive-type liquid crystaldisplay device according to the first embodiment of the presentinvention;

FIG. 6 is a cross-sectional view of a first modified example (twistedangle being set at about 0°) of the semi-transmissive-type liquidcrystal display device of FIG. 1;

FIG. 7 is a cross-sectional view of a second modified example (twistedangle being set at about 60°) of the semi-transmissive-type liquidcrystal display device of FIG. 1;

FIG. 8 is a cross-sectional view showing configurations of asemi-transmissive-type liquid crystal display device according to asecond embodiment of the present invention;

FIGS. 9A, 9B, and 9C are process charts illustrating the method ofmanufacturing the semi-transmissive-type liquid crystal display devicein order of step according to the second embodiment of the presentinvention;

FIGS. 10A and 10B are also process charts illustrating the method ofmanufacturing the semi-transmissive-type liquid crystal display devicein order of step according to the second embodiment of the presentinvention;

FIG. 11 is a cross-sectional view of a first modified example (twistedangle being set at about 0°) of the semi-transmissive-type liquidcrystal display device of FIG. 8;

FIG. 12 is a cross-sectional view of a second modified example (twistedangle being set at about 60°) of the semi-transmissive-type liquidcrystal display device of FIG. 8;

FIG. 13 is a plan view for showing a configuration of asemi-transmissive-type liquid crystal display device according to athird embodiment of the present invention;

FIGS. 14A, 14B, and 14C are process charts for illustrating the methodof manufacturing the semi-transmissive-type liquid crystal displaydevice in order of step according to the third embodiment of the presentinvention;

FIGS. 15A and 15B are also process charts illustrating the method ofmanufacturing the semi-transmissive-type liquid crystal display devicein order of step according to the third embodiment of the presentinvention;

FIG. 16 is a plan view of a semi-transmissive-type liquid crystaldisplay device according to a fourth embodiment of the presentinvention;

FIG. 17 is a cross-sectional view of the semi-transmissive-type liquidcrystal display device of FIG. 16 taken along a line C-C;

FIG. 18 is a plan view of an expanded structure of a main portion of thesemi-transmissive-type liquid crystal display device of the fourthembodiment of the present invention;

FIG. 19 is a cross-sectional view of the semi-transmissive-type liquidcrystal display device of FIG. 18 taken along a line D-D;

FIGS. 20A, 20B, 20C, and 20D are process charts illustrating a method ofmanufacturing the semi-transmissive-type liquid crystal display devicein order of step according to the fourth embodiment of the presentinvention;

FIGS. 21A and 21B are also process charts illustrating the method ofmanufacturing the semi-transmissive-type liquid crystal display devicein order of step according to the fourth embodiment of the presentinvention;

FIG. 22 is a plan view of a semi-transmissive-type liquid crystaldisplay device according to a fifth embodiment of the present invention;

FIG. 23 is a cross-sectional view of the semi-transmissive-type liquidcrystal display device of FIG. 22 taken along a line E-E;

FIG. 24 is a plan view of an expanded structure of a main portion of thesemi-transmissive-type liquid crystal display device of the fifthembodiment of the present invention;

FIG. 25 is a cross-sectional view of the expanded structure of the mainportion of the semi-transmissive-type liquid crystal display device ofFIG. 24 taken along a line F-F;

FIG. 26 is a plan view of an expanded structure of another main portionof the semi-transmissive-type liquid crystal display device of the fifthembodiment of the present invention;

FIG. 27 is a cross-sectional view of the expanded structure of the mainportion of the semi-transmissive-type liquid crystal display device ofFIG. 26 taken along a line G-G;

FIGS. 28A, 28B, 28C, and 28D are process charts illustrating a method ofmanufacturing the semi-transmissive-type liquid crystal display devicein order of step according to the fifth embodiment of the presentinvention;

FIGS. 29A and 29B are also process charts illustrating a method ofmanufacturing the semi-transmissive-type liquid crystal display devicein order of step according to the fifth embodiment of the presentinvention;

FIG. 30 is a plan view for showing configurations of a conventionalsemi-transmissive-type of a liquid crystal display device;

FIGS. 31A, 31B, and 31C are diagrams illustrating problematic points inthe conventional semi-transmissive-type liquid crystal display device;

FIG. 32 is a plan view of a semi-transmissive-type liquid crystaldisplay device for explaining a preface of the present invention;

FIG. 33 is a cross-sectional view of the semi-transmissive-type liquidcrystal display of FIG. 32 taken along a line H-H;

FIG. 34 is a diagram showing an outline of configurations of theconventional semi-transmissive-type liquid crystal display device neededto optimize intensity of outgoing light in its transmissive region andreflective region;

FIG. 35 is a diagram illustrating a relation between a twisted angle ofa liquid crystal and a layer thickness of the liquid crystal layer inthe conventional semi-transmissive-type liquid crystal display device ofFIG. 34; and

FIG. 36 is a diagram illustrating a relation among a twisted angle of aliquid crystal, a transmittance of the liquid crystal and a reflectivityof the liquid crystal in the conventional semi-transmissive-type liquidcrystal display device of FIG. 34.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Best modes of carrying out the present invention will be described infurther detail using various embodiments with reference to theaccompanying drawings.

First Embodiment

FIG. 1 is a plan view for showing a configuration of asemi-transmissive-type liquid crystal display device according to afirst embodiment of the present invention. FIG. 2 is a cross-sectionalview for showing a configuration of the semi-transmissive-type liquidcrystal display device of FIG. 1 taken along a line A-A. FIGS. 3A, 3B,and 3C are process charts illustrating a method of manufacturing thesemi-transmissive-type liquid crystal display device in order of stepaccording to the first embodiment of the present invention. FIGS. 4A and4B are process charts illustrating the method of manufacturing thesemi-transmissive-type liquid crystal display device in order of stepaccording to the first embodiment of the present invention. FIG. 5 is across-sectional view of another configuration of an active matrixsubstrate on the semi-transmissive-type liquid crystal display device ofFIG. 1. FIG. 6 is a cross-sectional view of a first modified example(twisted angle being set at about 0°) of the semi-transmissive-typeliquid crystal display device of FIG. 1. FIG. 7 is a cross-sectionalview of a second modified example (twisted angle being set at about 60°)of the semi-transmissive-type liquid crystal display device of FIG. 1.Moreover, in the example described below, a case is explained in which atwisted angle is set at about 72°, that is, a reflective gap is equal toa transmissive gap.

The semi-transmissive-type liquid crystal display device of the firstembodiment includes, as shown in FIG. 1 and FIG. 2, an active matrixsubstrate 12 on which a TFT 3 operating as a switching element isformed, a facing substrate 16, a liquid crystal layer 17 beingsandwiched between the active matrix substrate 12 and the facingsubstrate 16, a backlight source 18 placed on a rear face of the activematrix substrate 12, and phase difference plates (λ/4 plates) 20 a and20 b and polarizers 19 a and 19 b placed outside of the active matrixsubstrate 12 and the facing substrate 16, respectively.

The active matrix substrate 12 includes a transparent insulatingsubstrate 8, a gate line 1 and a data line (signal electrode) 2 formedon the transparent insulating substrate 8, a gate electrode (scanningelectrode) 1 a being connected to the gate line 1, a common storage line4, an auxiliary capacitive electrode 4 a, a gate insulating film 9, asemiconductor layer 3 a, a drain electrode 2 a and a source electrode 2b drawn from both ends of the semiconductor layer 3 a and connectedrespectively to the data line 2 and a pixel electrode (described later),a capacitive accumulating electrode 2 c, and a passivation film 10. Thepixel electrode is so constructed that there is a one-to-onecorrespondence to an intersecting point between the signal electrode 2and the scanning electrode 1. each of pixel regions PX is made up of atransmissive region PXa to allow light fed from the backlight source 18to transmit and a reflective region PXb to have incident ambient lightbe reflected and each of the transmissive region PXa and the reflectiveregion PXb is covered by a concave/convex shaped film 11 made of organicfilms or a like. In the reflective region PXb, a reflective film 6(since it is not necessary for a metal film formed in the reflectiveregion PXb to be used as an electrode and, in this embodiment, it issimply called a “reflective film 6” accordingly) made of Al or an Alalloy is formed and a transparent electrode film 5 made of ITO (IndiumTin Oxide) or a like is formed throughout the pixel region PX in amanner so as to cover all surfaces of the reflective film 6 through asecond passivation film 24 being sandwiched between the transparentelectrode film 5 and the reflective film 6. The transparent electrodefilm 5 being connected to the source electrode 2 b through a contacthole 7 operates as a pixel electrode and an orientated film 29 made ofpolyimide or a like is formed on the transparent electrode film 5. TheTFT 3 consists of the gate electrode 1 a, gate insulating film 9,semiconductor layer 3 a, drain electrode 2 a, and source electrode 2 b.On the other hand, the facing substrate 16 includes a transparentinsulating substrate 13, a color filter 14, a black matrix (not shown),a facing electrode 15, and the orientated film 29.

As described above, by forming the transparent electrode film 5 over thereflective film 6 through the second passivation film 24 beingsandwiched between the transparent electrode film 5 and the reflectivefilm 6, ITO making up the transparent electrode film 5 is not formed atthe time of formation of a resist pattern used to process the reflectivefilm 6 and, therefore, even if a developer permeates through a pinholeof Al, no electric erosion reaction occurs, thus enabling prevention ofoccurrence of a pixel defect such as peeling or a like. However, only ifthe reflective film 6 and the transparent electrode film 5 are stackedin layers in a way being reverse to that employed in the conventionalsemi-transmissive-type liquid crystal display device, when there existsa region in which coverage by the transparent electrode film 5 in an endportion of the reflective film 6 is insufficient at the time offormation of a resist pattern used to process the transparent electrodefilm 5, Al film of the lower layer comes into contact with thedeveloper, as a result, causing an electric erosion reaction and erosionof Al and/or ITO.

To solve this problem, in the first embodiment, when the transparentelectrode film 5 is formed on the reflective film 6, a layout is made ina manner that the reflective film 6 and the transparent electrode film 5overlap over all portions surrounding the reflective film 6. Moreparticularly, as shown in FIG. 1 and FIG. 2, the reflective film 6 isformed in the reflective region PXb containing an upper layer on the TFT3 and the transparent electrode film 5 is formed throughout the pixelregion PX in a manner so as to fully cover the reflective films (lowerlayer) 6.

Therefore, since, at the time of formation of a resist pattern to beused for processing of the transparent electrode film 5, the reflectivefilm 6 is fully covered by the transparent electrode film 5 with thesecond passivation film 24 being sandwiched between the transparentelectrode film 5 and the reflective film 6, Al film can avoid contactwith the developer. This enables an electric erosion reaction between Aland ITO to be surely prevented and occurrence of a failure caused by theelectric erosion reaction to be avoided.

Moreover, as described above, by covering the TFT 3 with the reflectivefilm 6, even when light from an outside enters TFT 3, the reflectivefilm 6 successfully intercepts the incident light. This can preventinconvenience in which an OFF current of the TFT 3 is increased by aphotoelectric effect caused by the incident light and an operationalfailure occurs. However, there is a fear that, if a distance between thereflective film 6 and the TFT 3 is short, due to an influence by avoltage (gate voltage in particular) applied to the TFT 3, a potentialof the reflective film 6 being floating electrically fluctuates, whichdisturbs a controlled electric field of a liquid crystal. To solve thisproblem, in the embodiment, by forming the concave/convex shaped film 11also on the TFT 3, the distance between the TFT 3 and the reflectivefilm 6 is made longer, which serves to reduce the influence by thevoltage to be applied to the above TFT 3 on the reflective film 6.

Moreover, since the reflective film 6 is covered with the transparentelectrode film 5 with the second passivation film 24 being interposedbetween the reflective film 6 and the transparent electrode film 5,polyimide film making up the orientated film 29 formed on an upper faceof the active matrix substrate 12 can avoid contact with Al making upthe reflective film 6 and, therefore, accumulation of electric chargeswithin polyimide can be inhibited and occurrence of a flicker caused bya residual DC voltage can be prevented, thus enabling a simultaneoussolution of the two problems including the electric erosion reaction andthe flicker is made possible.

Also, in the embodiment, though polyimide film making up the orientatedfilm 29 can avoid contact with Al film making up the reflective film 6and, since an ITO film making up the transparent conductive film 5 isformed on an upper surface of the active matrix substrate 12, ITO comesinto contact with polyimide film. However, since ITO is not oxidized, noSchottky barrier is produced and, since an electron produced due torubbing processing or a like goes out from ITO to an outside, a residualDC voltage does not occur.

Furthermore, a relation between the reflective film 6 and thetransparent electrode film 5 in the semi-transmissive-type liquidcrystal display device is applied to each pixel or each segment(sub-pixel) making up a pixel. This is the same in other embodimentsdescribed later.

The method for manufacturing the semi-transmissive-type liquid crystaldisplay device of the embodiment is described below in order of step byreferring to FIGS. 3 and 4. Moreover, in addition to the method formanufacturing the above semi-transmissive-type liquid crystal displaydevice, a method of manufacturing the G-D converting portion in whichG-D conversion is made is also explained. The G-D converting portion isrequired to prevent a short among drawing wirings by a conductive seal.A function of the G-D converting portion is that, when a drain electrodehas to be electrically drawn to an outside, since it is difficult todirectly draw it due to a structural restraint including occurrence of ashort, the drain electrode is drawn using a gate layer through atransparent electrode film.

First, as shown in FIG. 3A, by having metal such as Cr (Chromium)deposited entirely on the transparent insulating substrate 8 made ofglass or a like and by removing unwanted metal by using knownphotolithography and etching methods, the gate line 1 (not shown), thegate electrode 1 a, the common storage line 4 (not shown), and theauxiliary capacitive electrode 4 a (not shown) are formed. Componentsnot shown in FIG. 3 are shown in FIG. 1. Next, the gate insulating film9 made of SiO₂ (Silicon Dioxide), SiN_(x) (Silicon Nitride), SiO_(x)(Silicon Oxide), or a like is formed on all surfaces of the transparentinsulating substrate 8. Then, after having a-Si (amorphous silicon) or alike deposited on all surfaces of the gate insulating film 9, patterningoperations are performed to form an island portion which operates as thesemiconductor layer 3 a. Next, after having metal such as Cr depositedon all surfaces thereof, patterning operations are performed to form thedata line 2 (not shown), the drain electrode 2 a, the source electrode 2b, and the capacitive accumulating electrode 2 c (not shown). The TFThas been now formed by processes described above. Then, in order toprotect the TFT 3, the passivation film 10 made of an SiN_(x) film or alike is deposited on all surfaces thereof by using a plasma CVD(Chemical Vapor Deposition) method or a like. Moreover, outside of thepixel region PX above the transparent insulating substrate 8, the G-Dconverting portion described above and a terminal portion are formed.

Next, as shown in FIG. 3B, by coating the passivation film 10 with aphotosensitive acrylic resin (such as PC403, 415G, 405G or a likemanufactured by JSR Co., Ltd in Japan) by using a spin coating method,the concave/convex shaped film 11 is formed in the pixel region PX. Anaim of forming the concave/convex shaped film 11 is to enhancevisibility of reflected light produced when ambient light having enteredthe reflective region PXb is reflected off the reflective film 6therein. Moreover, a concave portion in the concave/convex shaped film11 made of the photosensitive acrylic resin is exposed to acomparatively small amount of light and a convex portion is not exposedto light. A region making up the contact hole 7, G-D converting portion,and terminal portion are exposed to a comparatively large amount oflight.

Such the exposure process can be performed by using a half-tone(gray-tone) mask having, for example, a reflective film formed in aportion corresponding to the above convex portion of the concave/convexshaped film, a transmissive film formed in a portion corresponding tothe contact hole, G-D converting portion, and terminal portion, and asemi-transmissive film formed in a portion corresponding to the concaveportion of the concave/convex shaped film. Thus, the half-tone maskenables a concave and convex portion to be formed by one-time exposure.Moreover, the concave and convex portion can be formed even by usingonly the reflective film 6 and a transmissive film as a photomask. Also,the concave and convex portion can be formed by making exposureseparately on the contact hole 7 and on the concave portion and bychanging an amount of light to be used for the exposure.

Then, concave and convex portions are formed by making use of adifference in speed of dissolution by an alkaline developer in each ofthe concave portion, convex portion, contact hole 7, or a like.Moreover, in FIG. 3B, the concave and convex shaped film 11 is formed inthe entire pixel region PX including the reflective region PXb andtransmissive region PXa, however, a surface of the concave/convex shapedfilm 11 to be formed in the transmissive region PXa can be made flatwithout forming a concave and convex portion. Moreover, when theconcave/convex shaped film 11 is formed also on the transmissive regionPXa, in order to suppress an attenuation of transmitted light caused bythe concave/convex shaped film 11, exposure processing is performed onall the surfaces thereof and decoloring process is performed on theacrylic film. Then, by curing, for example, at 220° C. for about onehour, the concave/convex shaped film 11 having a desired shape can beformed.

As described above, if an interval between the TFT 3 and the reflectivefilm 6 to be formed on the TFT 3 is small, a potential of the reflectivefilm 6 fluctuates due to a gate voltage applied to the TFT 3 or a like,which disturbs a controlled electric field of a liquid crystal anddegrades display quality. Therefore, in the embodiment, theconcave/convex shaped film 11 is formed also on the TFT 3.

Next, as shown in FIG. 3C, after having Al deposited on all the surfacesthereof by using a sputtering method or an evaporation method, bycovering only the reflective region PXb in the pixel region PX with aresist pattern and by patterning dry or wet etching partially on theexposed Al, the reflective film 6 is formed. At this point, thereflective film 6 is formed also on the TFT 3 so that light from anoutside is not incident on the TFT 3. In this case, the reflective film6 is formed in regions inside of the gate line 1 and the data line 2 sothat an influence by the gate line 1 and the data line 2 is suppressedand the TFT 3 and the concave/convex shaped film 11 are completelycovered by the transparent electrode film 5. Moreover, as a material forthe reflective film 6, Al or an Al alloy is used in ordinary cases,however, the present invention is not limited to this, that is, anymetal, so long as it has high reflectivity and so long as it can besuitably used for a liquid crystal manufacturing process, may beemployed.

Next, as shown in FIG. 4A, after having had an insulating film made ofSiO, deposited on all the surfaces thereof using a plasma CVD method, byforming a resist pattern on the insulating film, the second passivationfilm 24 is formed. Then, by performing selective etching on exposedportions of the second passivation film 24, passivation film 10, andgate insulating film 9, the contacy holes 7 are formed, whereby thesource electrode 2 b is exposed through each of the contact holes 7. Atthis time, the contact holes 7 are not formed only in the pixel region,but also in the G-D converting portion and the terminal portion.

Next, as shown in FIG. 4B, after having had a transparent conductivefilm made of ITO or a like deposited on all the surfaces thereof byusing a sputtering method, by using a resist pattern, the transparentelectrode film 5 covering all surfaces of each pixel, a G-D convertingelectrode 22, and a terminal electrode 23 are formed at a same time. Atthis point, in order to prevent an electric erosion reaction of thereflective film 6 serving as a lower layer, the transparent electrodefilm 5 is formed in a manner so as to extend, for example, to regions onthe gate line 1 and the data line 2 so that all surfaces of thereflective film 6 are covered. By employing the layer-stacked structureand layout structure of the reflective film 6 and the transparentelectrode film 5, the reflective film 6 can avoid contact with thedeveloper.

In the embodiment, since the second passivation film 24 is formedbetween the reflective film 6 and the transparent electrode film 5,causing the reflective film 6 to be put in an electrically floatingstate, there is a fear that a potential of the reflective film 6fluctuates due to a gate voltage to be applied to the TFT 3. However, asdescribed above, by forming a concave/convex shaped film 11 on the TFT 3and by keeping a distance between the TFT 3 and the reflective film 6using the concave/convex shaped film 11, it is made possible to fullyreduce an influence by the TFT 3 on the reflective film 6.

Then, the orientated film 29 made of polyimide is formed on thetransparent electrode film 5 to complete the formation of the activematrix substrate 12. Next, a facing substrate 16 is prepared whichincludes the color filter 14, black matrix (not shown), facing electrode15, orientated film 29 having been formed sequentially on thetransparent insulating substrate 13. Then, by inserting the liquidcrystal layer 17 between the active matrix substrate 12 and the facingsubstrate 16 and by placing phase difference plates 20 a and 20 b andpolarizers 19 a and 19 b on both sides of the active matrix substrate 12and facing substrate 16 respectively and by placing the backlight source18 on a rear of the polarizer 19 a placed on a side of the active matrixsubstrate 12, the semi-transmissive-type liquid crystal display deviceas shown in FIGS. 1 and 2 is manufactured.

Thus, according to the semi-transmissive-type liquid crystal displaydevice and the method of manufacturing the same of the embodiment, sincethe transparent electrode film 5 is formed above the reflective layer 6with the second passivation film 24 being sandwiched between thereflective film 6 and the transparent electrode film 5, an electricerosion reaction between Al and ITO can be avoided and occurrence of apixel defect can be prevented and, since polyimide film (orientated film29) can avoid contact with Al film (reflective film 6) and, a flickercaused by a residual DC voltage can be prevented. Also, G-D conversioncan be made in the outer regions of the liquid crystal panel.

Moreover, in the embodiment, an example is shown in which the secondpassivation film 24 is placed both in the reflective region PXb and thetransmissive region PXa. However, since the second passivation film 24is placed with an aim of avoiding direct contact of the reflective film6 with the transparent electrode film 5, as shown in FIG. 5, the secondpassivation film 24 may be formed only on the reflective film 6. In thiscase, after an SiN_(x) film has been formed in the process shown in FIG.4A, before contact holes 7 are formed not only on the source electrode 2b, but in the G-D converting portion and the terminal portion, thesecond passivation film 24 in the transmissive region PXa is removed byusing a resist pattern as a mask. Also, after having consecutivelyformed Al and SiN_(x) films and removed the second passivation film 24and the reflective film 6 in the transmissive region PXa at a same timeby using a resist pattern as a mask, and thereafter almost the sameprocess as described above may be performed. Thus, the active matrixsubstrate 12 having configurations as shown in FIG. 5 is finallycompleted and the semi-transmissive-type liquid crystal display deviceusing this active matrix substrate 12 can be manufactured.

Moreover, in the semi-transmissive-type liquid crystal display device ofthe embodiment, since a liquid crystal having a twisted angle being setat about 72° is used, a reflective gap “dr” is made equal to atransmissive gap “df”, that is, a film thickness of the concave andconvex shaped film 11 formed in the reflective region PXb is equal tothat of the concave and convex shaped film 11 formed in the transmissiveregion PXa. However, as shown in the conventional technology, even if atwisted angle is set at about 0° or at about 60°, by changing thereflective gap “dr” and the transmissive gap “df”, optimum intensity ofoutgoing light can be obtained.

FIG. 6 is a cross-sectional view of a first modified example of thesemi-transmissive-type liquid crystal display device of the embodiment.In the semi-transmissive-type liquid crystal display device of the firstmodified example, by setting a twisted angle of a liquid crystal atabout 0° and by forming the concave/convex shaped film 11 only in thereflective region PXb and by setting a thickness of the concave/convexshaped film 11 at about 1.4 μm (2.9 μm−1.5 μm), the reflective gap “dr”is optimized so as to become about 1.5 μm. This structure can beachieved by adjusting conditions for applying a photosensitive acrylicresin so that a thickness of the concave/convex shaped film 11 becomesabout 1.4 μm when the concave/convex shaped film 11 is formed, forexample, in the process shown in FIG. 3B and by simultaneously removingthe concave/convex shaped film 11 in the transmissive region PXa whenthe contact hole 7 is formed on the source electrode 2 b. Then, byperforming approximately the same process as described above, thesemi-transmissive-type liquid crystal display device having its twistedangle being set at about 0°, having its reflective gap “dr” being about1.5 μm and having its transmissive gap “df” being about 2.9 μm ismanufactured finally as shown in FIG. 6.

FIG. 7 is a cross-sectional view of a second modified example of thesemi-transmissive-type liquid crystal display device of the embodiment.

In the semi-transmissive-type liquid crystal display device of thesecond modified example, as shown in FIG. 7, by setting a twisted angleof its liquid crystal at about 60° and by forming the concave/convexshaped film 11 both in the reflective region PXb and in the transmissiveregion PXa and by setting a thickness of the concave/convex shaped film11 in the transmissive region PXa to become slightly thin, optimizationis achieved so that its reflective gap “dr” is about 2.0 μm and itstransmissive gap “df” is about 2.8 μm. In this case, the reflective gap“dr” accounts for about 70% of the transmissive gap “df”. To achievethis structure, since a thickness of a photosensitive acrylic resincannot be controlled exactly, as shown in FIG. 7, after having formedthe concave/convex shaped film 11 both in the reflective region PXb andin the transmissive region PXa (whether or not concave and convexportions exist on a surface of the transmissive region PXa presents noproblem), by forming a hollow having a depth of about 0.8 μm (2.8 μm−2.0μm) only in the transmissive region PXa of the facing substrate 16, itstransmissive gap is preferably calibrated. Moreover, this structure canbe achieved by forming a hollow in the color filter 14 while beingfabricated and by forming, in advance, a hollow in the transparentinsulating substrate 13. Then, by performing approximately the sameprocess as described above, the semi-transmissive-type liquid crystaldisplay device having its twisted angle being set at about 60° and itsreflective gap “dr” being about 2.0 μm and its transmissive gap “df”being about 2.8 μm is manufactured finally as shown in FIG. 7.

Second Embodiment

FIG. 8 is a cross-sectional view showing configurations of asemi-transmissive-type liquid crystal display device according to asecond embodiment of the present invention. FIGS. 9A, 9B, and 9C areprocess charts illustrating a method of manufacturing thesemi-transmissive-type liquid crystal display device in order of stepaccording to the second embodiment of the present invention. FIGS. 10Aand 10B are process charts illustrating the method of manufacturing thesemi-transmissive-type liquid crystal display device in order of stepaccording to the second embodiment. FIG. 11 is a cross-sectional view ofa first modified example (twisted angle being set at about 0°) of thesemi-transmissive-type liquid crystal display device of FIG. 8. FIG. 12is a cross-sectional view of a second modified example (twisted anglebeing set at about 60°) of the semi-transmissive-type liquid crystaldisplay device of FIG. 8. Configurations of the semi-transmissive-typeliquid crystal display device of the second embodiment differ greatlyfrom those of the first embodiment in that, in order to simplifymanufacturing processes, formation of a second passivation film is madeunnecessary and a transparent electrode film 5 is formed directly on areflective film 6. Moreover, in the example described below, a case isexplained in which a twisted angle is set at about 72°, that is, areflective gap is equal to a transmissive gap. In thesemi-transmissive-type liquid crystal display device of the secondembodiment, as shown in FIG. 8, the reflective film 6 made of Al or anAl alloy is formed in a reflective region PXb of a pixel region PX, andthe transparent electrode film 5 made of ITO or a like is formedthroughout the pixel region PX in a manner so as to fully cover thereflective films (lower layer) 6, thus a transmissive region PXa isformed in the pixel region PX except the reflective region PXb.Moreover, in the embodiment, as described later, the reflective film 6is connected to the transparent electrode film 5 and is used as part ofa pixel electrode. Configurations other than described above are thesame as in the first embodiment. Therefore, in FIG. 8, same referencenumbers are assigned to components corresponding to those in FIG. 1 andtheir descriptions are omitted accordingly.

Next, a method for manufacturing the semi-transmissive-type liquidcrystal display device of the second embodiment is described in order ofstep by referring to FIGS. 9A, 9B, and 9C and FIGS. 10A and 10B. First,as in the case of the first embodiment, as shown in FIG. 9A, after agate line 1 (not shown), a gate electrode 1 a, a common storage line 4(not shown), and an auxiliary capacitive electrode 4 a (not shown) havebeen formed on a transparent insulating substrate 8 made of glass or alike by approximately the same method as employed in the firstembodiment, a semiconductor layer 3 a is formed with a gate insulatingfilm 9 being interposed between the semiconductor layer 3 a and the gateelectrode 1 a. Next, a data line 2 (not shown), a drain electrode 2 a, asource electrode 2 b, and a capacitive accumulating electrode 2 c (notshown) are formed to construct a TFT 3 and then a passivation film 10 isformed. Components not shown in FIG. 9 are described in FIG. 1.

Next, as shown in FIG. 9B, by the same method as in the firstembodiment, after the passivation film 10 has been coated with aphotosensitive acrylic resin, the acrylic resin is removed from portionsof the contact hole 7, a G-D converting section placed outside of thepixel region PX and a terminal region, and then a concave/convex shapedfilm 11 is formed in the reflective region PXb and in the transmissiveregion PXa containing the TFT 3. In this case, in order to suppressattenuation of transmitted light caused by the concave/convex shapedfilm 11, it is preferable that exposure processing is performed on allsurfaces thereof and decoloring of the acrylic film is made.

Then, as shown in FIG. 9C, by approximately the same method employed inthe first embodiment, after Al has been formed on all the surfacesthereof, Al in the transmissive region PXa is removed by using a resistpattern as a mask and the reflective film 6 is formed only in thereflective region PXb. At this point, to prevent light fed from anoutside from entering the TFT 3, it is preferable that the reflectivefilm 6 is formed on the TFT 3.

Then, as shown in FIG. 10A, by performing selective etching on thepassivation film 10 formed below the contact hole 7, passivation film 10in the G-D converting portion and in the terminal portion and gateinsulating film 9, the source electrode 2 b is made exposed and contactholes 7 are formed also in the G-D converting portion and in theterminal portion.

Then, as shown in FIG. 10B, after an ITO film has been formed on allsurfaces thereof, by using a resist pattern as a mask, the transparentelectrode film 5 (as a pixel electrode) on the reflective film 6 of thereflective region PXb as well as the transmissive region Pxa in thepixel region, G-D converting electrode 22, and terminal electrode 23 areformed at a same time. In the second embodiment, unlike in the case ofthe first embodiment, since the reflective film 6 is not covered with asecond passivation film 24, if a portion exists in which the reflectivefilm 6 is not covered with the transparent electrode film 5 and when aregion occurs in which coverage by the transparent electrode film 5 inan end of the reflective film 6 is insufficient when a resist patternused for processing a transparent electrode film is formed, there is afear that an electric erosion reaction occurs. Therefore, thetransparent electrode film 5 has to be formed so as to cover entireportions of the reflective film 6, that is, the transparent electrodefilm 5 has to be formed in a manner that a resist pattern is left onentire portions of the reflective film 6.

Moreover, in the first embodiment, since the second passivation film 24is formed between the reflective film 6 and the transparent electrodefilm 5 and the reflective film 6 is in an electrically floating state,there is a fear that a potential of the reflective film 6 fluctuates dueto a gate voltage applied to the TFT 3. However, in the secondembodiment, since the reflective film 6 is electrically connected to thetransparent electrode film 5, no fluctuation occurs in a potential ofthe reflective film 6. Therefore, since it is not necessary to keep adistance between the TFT 3 and the reflective film 6, formation of theconcave/convex shaped film 11 on the TFT 3 is not required.

Thereafter, by forming an orientated film made of polyimide on thetransparent electrode film 5 in approximately the same way as employedin the first embodiment, formation of the active matrix substrate 12 iscompleted. Then, a facing substrate 16 is prepared which includes acolor filter 14, black matrix (not shown), facing electrode 15,orientated film 29 having been formed sequentially on the transparentinsulating substrate 13. Then, by inserting the liquid crystal layer 17between the active matrix substrate 12 and the facing substrate 16 and,in approximately the same way employed in the first embodiment, byplacing phase difference plates 20 a and 20 b and polarizers 19 a and 19b on both sides of the active matrix substrate 12 and facing substrate16 respectively and by placing a backlight source 18 on a rear of thepolarizer 19 a placed on a side of the active matrix substrate 12, thesemi-transmissive-type liquid crystal display device as shown in FIG. 8is manufactured. That is, in approximately the same way as employed inthe first embodiment, by inserting a liquid crystal having its twistedangle being set at about 72°, the semi-transmissive-type liquid crystaldisplay device having no step between the reflective region PXb and thetransmissive region PXa (the reflective gap dr and the transmissive gapdf are the same which is about 2.7 μm) is manufactured. However, thephase difference plates 20 a and 20 b, polarizers 19 a and 19 b, andbacklight source 18 are not shown in FIG. 8.

Thus, according to the semi-transmissive-type liquid crystal displaydevice of the second embodiment, since the transparent electrode film 5is formed above the reflective film 6 in a manner so as to cover thereflective film 6, an electric erosion reaction between Al and ITO canbe avoided and occurrence of a pixel defect can be also prevented.Moreover, since Al does not come into contact with polyimide, occurrenceof a flicker caused by a residual DC voltage can be prevented. Moreover,G G-D conversion can be made in the outer regions of the liquid crystalpanel.

Moreover, also in the second embodiment, as in the case of the firstembodiment, a modified configuration is possible in which a twistedangle of a liquid crystal is set at about 0° or about 60°. FIG. 11 is across-sectional view of a first modified example (its twisted anglebeing set at about 0°) of the semi-transmissive-type liquid crystaldisplay device of the second embodiment. This structure can be achievedby adjusting conditions for applying a photosensitive acrylic resin sothat a thickness of the concave/convex shaped film 11 becomes about 1.4μm when the concave/convex shaped film 11 is formed in the process shownin FIG. 9A and by removing the concave/convex shaped film 11 in thetransmissive region PXa when the contact hole 7 is formed on the sourceelectrode 2 b. Then, by performing approximately the same process asdescribed above, the semi-transmissive-type liquid crystal displaydevice having its twisted angle being set at about 0°, its reflectivegap “dr” being about 1.5 μm and its transmissive gap “df” being about2.9 μm is manufactured finally as shown in FIG. 11.

FIG. 12 is a cross-sectional view of a second modified example (itstwisted angle being set at about 60°) of the semi-transmissive-typeliquid crystal display device of the second embodiment. This structurecan be achieved by forming the concave/convex shaped film 11 in both thereflective region PXb and the transmissive region PXa (existence ofconcave and convex portions on a surface in the transmissive region PXapresents no problem) and by placing a hollow in the transmissive regionPXa of the facing substrate 16 to calibrate a gap. Then, by performingapproximately the same process as described above, thesemi-transmissive-type liquid crystal display device having its twistedangle being set at about 60°, its reflective gap “dr” being about 2.0 μmand its transmissive gap “df” being about 2.8 μm is manufactured.

Third Embodiment

FIG. 13 is a plan view of a semi-transmissive-type liquid crystaldisplay device according to a third embodiment of the present invention.FIGS. 14A, 14B, and 14C are process charts illustrating the method ofmanufacturing the semi-transmissive-type liquid crystal display devicein order of step according to the third embodiment. FIGS. 15A and 15Bare process charts illustrating the method of manufacturing thesemi-transmissive-type liquid crystal display device in order of stepaccording to the third embodiment. Configurations of thesemi-transmissive-type liquid crystal display of the third embodimentdiffer from those in the first embodiment in that, in order to preventfluctuation in a potential of a reflective film, the reflective film isconnected to a transparent electrode film through a contact hole(reflective film connecting portion). In the semi-transmissive-typeliquid crystal display device of the third embodiment, as shown in FIG.13, a reflective film 6 made of Al or an Al alloy is formed in areflective region PXb and the reflective film 6 is connected to atransparent electrode film 5 through a reflective film connectingportion 25 formed in a second passivation film 24. Configurations otherthan described above are the same as in the first embodiment. Therefore,in FIG. 13, same reference numbers are assigned to componentscorresponding to those in FIG. 1 and their descriptions are omittedaccordingly.

Next, a method for manufacturing the semi-transmissive-type liquidcrystal display device of the third embodiment is explained in order ofstep by referring to FIGS. 14A to 14C and FIGS. 15A and 15B. FIGS. 14Ato 14C and FIGS. 15A and 15B are cross-sectional views of thesemi-transmissive-type liquid crystal display device of FIG. 13 takenalong a line B-B.

First, as shown in FIG. 14A, in approximately the same method asemployed in the first and second embodiments, after a gate line 1 (notshown), a gate electrode 1 a, a common storage line 4 (not shown), andan auxiliary capacitive electrode 4 a have been formed, a semiconductorlayer 3 a is formed with a gate insulating film 9 being interposedbetween the semiconductor layer 3 a and the gate electrode 1 a. Next, adata line 2 (not shown), a drain electrode 2 a, a source electrode 2 b,and a capacitive accumulating electrode 2 c (not shown) are formed toconstruct a TFT 3 and then a passivation film 10 is formed.

Next, as shown in FIG. 14B, by the same method as in the firstembodiment, after the passivation film 10 has been coated with aphotosensitive acrylic resin, a acrylic resin is removed from a contacthole 7 formed in the pixel region PX, the G-D converting section and theterminal region placed outside of a pixel region PX, and aconcave/convex shaped film 11 is formed in a reflective region PXb andin a transmissive region PXa containing the TFT 3. In this case, inorder to suppress attenuation of transmitted light caused by theconcave/convex film 11, it is preferable that exposure processing isperformed on all surfaces thereof and decoloring of the acrylic film isperformed.

Next, as shown in FIG. 14C, by approximately the same method employed inthe first and second embodiments, after Al has been formed on all thesurfaces thereof, Al in the transmissive region PXa is removed by usinga resist pattern as a mask and the reflective film 6 is formed in thereflective region PXb. At this point, in order to prevent light fed froman outside from entering the TFT 3, it is preferable that the reflectivefilm 6 is formed on the TFT 3.

Then, as shown in FIG. 15A, after an insulating film made of SiO, hasbeen deposited on all the surfaces thereof by using a plasma CVD methodor a like, a resist pattern is formed on the insulating film and then asecond passivation film 24 is formed thereon. Next, selective etching isperformed on the second passivation film 24 below the contact hole 7 andthe second passivation film 24 in the G-D converting portion and in theterminal portion and, at a same time, the reflective film connectingportion 25 is formed to have the reflective film 6 be exposed to thesecond passivation film 24. Then, selective etching is performed on thepassivation film 10 below the contact hole 7, the passivation film 10 inthe G-D converting portion and in the terminal portion, and the gateinsulating film 9 to have the source electrode 2 b be exposed and then acontact hole is formed at a same time in the G-D converting portion andin the terminal portion. Moreover, the reflective film connectingportion 25 can be formed at an arbitrary place on the reflective film 6,however, since there is a fear that Al is eroded by a developer whenetching is performed on the reflective film connecting portion 25, it ispreferable that the reflective film connecting portion 25 is formed in aplace surrounding each of the pixels. Etching on the second passivationfilm 24 and etching on the passivation film 10 and on the gateinsulating film 9 may be simultaneously performed.

Next, as shown in FIG. 15B, after a transparent conductive film made ofITO has been deposited on all the surfaces thereof by using a sputteringmethod, the transparent electrode film 5 formed throughout surface ofthe pixels, a G-D converting electrode 22 and a terminal electrode 23are formed using a resist pattern as a mask at a same time. By employingthe layer-stacked structure and layout structure of the reflective film6 and the transparent electrode film 5, the reflective film 6 can avoidcontact with the developer.

Moreover, in the first embodiment, since the reflective film 6 is in anelectrically floating state, there is a fear that a potential of thereflective film 6 fluctuates due to a gate voltage being applied to theTFT 3. However, in the third embodiment, as in the case of the secondembodiment, since the reflective film 6 is electrically connected to thetransparent electrode film 5, no fluctuation occurs in a potential ofthe reflective film 6. As a result, it is not necessary to keep adistance between the TFT 3 and the reflective film 6 and, therefore,formation of the concave and convex film 11 on the TFT 11 is notrequired.

Thereafter, by forming an orientated film 29 made of polyimide on thetransparent electrode film 5, formation of the active matrix substrate12 is completed. Next, a facing substrate 16 is prepared which includesthe color filter 14, black matrix (not shown), facing electrode 15,orientated film 29 having been formed sequentially on the transparentinsulating substrate 13. Then, by inserting the liquid crystal layer 17between the active matrix substrate 12 and the facing substrate 16 andby placing phase difference plates 20 a and 20 b and polarizers 19 a and19 b on both sides of the active matrix substrate 12 and facingsubstrate 16 respectively and by placing the backlight source 18 on arear of the polarizer 19 a placed on a side of the active matrixsubstrate 12, the semi-transmissive-type liquid crystal display deviceas shown in FIG. 13 is manufactured.

Thus, according to the semi-transmissive-type liquid crystal displaydevice of the third embodiment, since the transparent electrode film 5is formed throughout the pixel region PX in a manner so as to coverfully the reflective film 6, an electric erosion reaction between Al andITO can be avoided and occurrence of a pixel defect can be prevented.Moreover, since Al does not come into contact with polyimide, occurrenceof a flicker caused by a residual DC voltage can be prevented. Also, G-Dconversion can be made in the outer regions of the liquid crystal panel.

Fourth Embodiment

FIG. 16 is a plan view of a semi-transmissive-type liquid crystaldisplay device according to a fourth embodiment of the presentinvention. FIG. 17 is a cross-sectional view of thesemi-transmissive-type liquid crystal display device of FIG. 16 takenalong a line C-C. FIG. 18 is a plan view of an expanded structure of amain portion of the semi-transmissive-type liquid crystal display deviceof the fourth embodiment. FIG. 19 is a cross-sectional view of thesemi-transmissive-type liquid crystal display device of FIG. 18 takenalong a line D-D. FIGS. 20A, 20B, 20C, and 20D are process chartsillustrating a method of manufacturing the semi-transmissive-type liquidcrystal display device in order of step according to the fourthembodiment. FIGS. 21A and 21B are also process charts illustrating themethod of manufacturing the semi-transmissive-type liquid crystaldisplay device in order of step according to the fourth embodiment.Configurations of the semi-transmissive-type liquid crystal displaydevice of the fourth embodiment differ from those in the thirdembodiment in that, in order to prevent a fluctuation in a potential ofa reflective film, at two different points within a contact hole formedon a second passivation film, the reflective film and a transparentelectrode film are connected to a source electrode. In thesemi-transmissive-type liquid crystal display device of the fourthembodiment, as shown in FIG. 16 to FIG. 19, a transparent electrode film5 is formed above the reflective film 6 with a second passivation film24 being interposed between the reflective film 6 and the transparentelectrode film 5, as in the case of the first embodiment. Moreover, asin the case of the third embodiment, the reflective film 6 iselectrically connected to the transparent electrode film 5 and in afirst region 7 a within a contact hole 7 formed on the secondpassivation film 24 and, in a second region 7 b within the contact hole7, a source electrode 2 b is connected to the transparent electrode film5. Configurations other than described above are the same as in thethird embodiment. Therefore, in FIGS. 16 and 17, same reference numbersare assigned to components corresponding to those in FIG. 13 and theirdescriptions are omitted accordingly.

When the reflective film 6 made of Al is connected to the transparentelectrode film 5 made of ITO in order to prevent a fluctuation in apotential of the reflective film 6 as in the case of the thirdembodiment, in some cases, a non-conductor made of aluminum oxide or alike is formed at an interface surface between Al and ITO depending on aprocess selected and contact resistance between the reflective film 6and the transparent electrode film 5 becomes as high as 10 MΩ or more.Therefore, in this case, since a fluctuation in a potential of thereflective film 6 caused by an electrostatic characteristic in amanufacturing process of a liquid crystal panel cannot be fullysuppressed, a fear exists that display quality is degraded.

To solve this problem, in the fourth embodiment, at two different places(first region 7 a and second region 7 b) within the contact hole 7formed in the second passivation film 24, each of the reflective film 6and transparent electrode film 5 is connected to the source electrode 2b. By configuring as above, since the reflective film 6 is not directlyconnected to the transparent electrode film 5, such the high contactresistance as described above does not occur and a fluctuation in apotential of the reflective film 6 can be fully suppressed, thuspreventing degradation of display quality.

Next, a method for manufacturing the semi-transmissive-type liquidcrystal display device of the fourth embodiment is explained in order ofstep by referring to FIGS. 20 to 21. FIGS. 20 to 21 are cross-sectionalviews of the semi-transmissive-type liquid crystal display device ofFIG. 16 taken along a line C-C.

First, as shown in FIG. 20A, after a gate line 1 (not shown), a gateelectrode 1 a, a common storage line 4 (not shown), and an auxiliarycapacitive electrode 4 a (not shown) have been formed on a transparentinsulating substrate 8 made of glass or a like by approximately the samemethod as employed in the first to third embodiments, a semiconductorlayer 3 a is formed with a gate insulating film 9 being interposedbetween the semiconductor layer 3 a and the gate electrode 1 a. Next, adata line 2 (not shown), a drain electrode 2 a, a source electrode 2 b,and a capacitive accumulating electrode 2 c (not shown) are formed toconstruct a TFT 3 and then a passivation film 10 is formed.

Next, as shown in FIG. 20B, by the same method as in the first to thirdembodiments, after the passivation film 10 has been coated with aphotosensitive acrylic resin, a acrylic resin is removed from thecontact hole 7, a G-D converting section placed outside of the pixelregion PX and then a terminal region and a concave/convex shaped film 11is formed in a reflective region PXb and transmissive region PXacontaining the TFT 3. In this case, in order to suppress attenuation oftransmitted light caused by the concave/convex film 11, it is preferablethat exposure processing is performed on all surfaces thereof anddecoloring of the acrylic film is made.

Then, as shown in FIG. 20C, by removing the passivation film 10 placedbelow the contact hole 7 using a resist pattern formed on theconcave/convex shaped film 11 as a mask, only the source electrode 2 bis made exposed. At this point, the passivation film 10 in the G-Dconverting portion and in the terminal portion and the gate insulatingfilm 9 are not removed.

Next, as shown in FIG. 20D, after Al has been formed on all surfacesthereof, Al in the transmissive region PXa is removed by using a resistpattern as a mask and the reflective film 6 is formed in the reflectiveregion PXb. At this point, in order to prevent light from an outsidefrom entering the TFT 3, it is preferable that the reflective film 6 isformed also on the TFT 3.

Then, as shown in FIG. 21A, after an insulating film made of SiO, hasbeen deposited on all the surfaces thereof by using a plasma CVD methodor a like, a resist pattern is formed on the insulating film to form asecond passivation film 24. Next, selective etching is performed on thesecond passivation film 24 below the contact hole 7 and the secondpassivation film 24 in the G-D converting portion and in the terminalportion. Then, selective etching is performed on the passivation film 10below the contact hole 7, the passivation film 10 in the G-D convertingportion and in the terminal portion, and the gate insulating film 9 tohave the source electrode 2 b be exposed and, at a same time, a contacthole is also formed in the G-D converting portion and in the terminalportion. Moreover, etching on the second passivation film 24 and etchingon the passivation film 10 and on the gate insulating film 9 may besimultaneously performed.

Next, as shown in FIG. 21B, after a transparent conductive film made ofITO has been deposited on all the surfaces thereof by using a sputteringmethod, the transparent electrode film 5 formed throughout the pixelregions PX, a G-D converting electrode 22 and a terminal electrode 23are formed using a resist pattern as a mask at a same time.

Then, the orientated film 29 made of polyimide is formed on the activematrix substrate 12 to complete the formation of the active matrixsubstrate 12. Next, a facing substrate 16 is prepared which includes thecolor filter 14, black matrix (not shown), facing electrode 15,orientated film 29 having been formed sequentially on the transparentinsulating substrate 13. Then, by inserting the liquid crystal layer 17between the active matrix substrate 12 and the facing substrate 16 andby placing phase difference plates 20 a and 20 b and polarizers 19 a and19 b on both sides of the active matrix substrate 12 and facingsubstrate 16 respectively and by placing the backlight source 18 on arear of the polarizer 19 a placed on a side of the active matrixsubstrate 12, the semi-transmissive-type liquid crystal display deviceas shown in FIG. 16 and FIG. 17 is manufactured.

Thus, according to the semi-transmissive-type liquid crystal displaydevice of the fourth embodiment and its manufacturing method, by formingthe transparent electrode film 5 above the reflective film 6 with thesecond passivation film 24 being interposed between the reflective film6 and the transparent electrode film 5 and by connecting the reflectivefilm 6 and transparent electrode film 5 to the source electrode 2 b attwo different points within the contact hole 7 formed in the secondpassivation film 24 to prevent a fluctuation of a potential of thereflective film 6, contact resistance between the reflective film 6 andthe transparent electrode film 5 is made lowered, which serves toimprove display quality.

Fifth Embodiment

FIG. 22 is a plan view of a semi-transmissive-type liquid crystaldisplay device according to a fifth embodiment of the present invention.FIG. 23 is a cross-sectional view of the semi-transmissive-type liquidcrystal display device of FIG. 22 taken along a line E-E. FIG. 24 is aplan view of an expanded structure of a main portion of thesemi-transmissive-type liquid crystal display device of the fifthembodiment. FIG. 25 is a cross-sectional view of the expanded structureof the main portion of the semi-transmissive-type liquid crystal displaydevice of FIG. 24 taken along a line F-F. FIG. 26 is a plan view of anexpanded structure of another main portion of the semi-transmissive-typeliquid crystal display device of the fifth embodiment of the presentinvention. FIG. 27 is a cross-sectional view of the expanded structureof the main portion of the semi-transmissive-type liquid crystal displaydevice of FIG. 26 taken along a line G-G. FIGS. 28A, 28B, 28C, and 28Dare process charts illustrating a method of manufacturing thesemi-transmissive-type liquid crystal display device in order of stepaccording to the fifth embodiment. FIGS. 29A and 29B are also processcharts illustrating a method of manufacturing the semi-transmissive-typeliquid crystal display device in order of step according to the fifthembodiment. Configurations of the semi-transmissive-type liquid crystaldisplay device of the fifth embodiment differ from those in the abovefourth embodiment in that, in order to prevent a fluctuation of apotential of the reflective film, two contact holes are formed in asecond passivation film and, in each of the contact holes, thereflective film and transparent electrode film are connectedrespectively to the source electrode. In the semi-transmissive-typeliquid crystal display device of the fifth embodiment, as shown in FIG.22 to FIG. 27 and as in the case of the first embodiment, thetransparent electrode film 5 is formed above the reflective film 6 withthe second passivation film 24 being interposed between the reflectivefilm 6 and the transparent electrode film 5 and, as in the case of thefourth embodiment, each of the reflective film 6 and the transparentelectrode film 5 is connected to the source electrode 2 b, and thesource electrode 2 b is connected to the transparent electrode film 5through a first contact hole 7A formed in the second passivation film 24and the source electrode 2 b is connected to the reflective film 6through a second contact hole 7B formed in the second passivation film24.

Moreover, FIGS. 24 to 27 show positional relations among the passivationfilm 10 in the first and second contact hole 7A and 7B, concave/convexshaped film 11, reflective film 9, second passivation film 24 andtransparent electrode film 5. That is, in the first contact hole 7A, theconcave/convex shaped film 11 is placed in its most outer region and, inan inside of the concave/convex shaped film 11 are placed the reflectivefilm 6, passivation film 10, second passivation film 24, and transparentelectrode film 5. In the second contact hole 7B, the concave/convexshaped film 11 is placed in its most outer region and, in an inside ofthe concave/convex shaped film 11 are placed the passivation film 10,reflective film 6, second passivation film 24, and transparent electrodefilm 5. As shown in FIG. 25, the transparent electrode film 5 isconnected to the source electrode 2 b and, as shown in FIG. 27, thereflective film 6 is connected to the source electrode 2 b. Moreover, asshown in FIG. 25, in the first contact hole 7A, if the reflective film 6is placed outside of the concave/convex shaped film 11, since there is afear that stepping of the transparent electrode film 5 occurs due to astep of the reflective film 6 and due to a sharp inclination caused by aconcave and convex portion of the concave and convex shaped film 11, itis preferable that the reflective film 6 is placed inside of theconcave/convex shaped film 11.

If, in order to prevent a fluctuation in a potential of the reflectivefilm 6, the reflective film 6 and transparent electrode film 5 areconnected to the source electrode 2 b at two different points (firstregion 7 a and second region 7 b) within the contact hole formed in thesecond passivation film 24 as in the case of the fourth embodiment, itis necessary to make large a diameter of the contact hole 7, whichcauses a freedom in arrangement positions of the contact hole 7 to bereduced and a reflection characteristic to be lowered.

To solve this problem, in the fifth embodiment, the reflective film 6 isconnected to the source electrode 2 b in the first contact hole 7Aformed in the second passivation film 24 and the transparent electrodefilm 5 is connected to the source electrode 2 b in the second contacthole 7B formed in the first passivation film 24. Since this enables thediameters of the first contact hole 7A and of the second contact hole 7Bto be decreased, a freedom in arrangement positions in each of the firstcontact hole 7A and second contact hole 7B is increased. Therefore,since each of the first contact hole 7A and the second contact hole 7Bcan be placed in a portion (flat part in the concave and convexportions) not being attributable to a reflection characteristic, out ofthe concave and convex portions of the reflective film 6, it is madepossible to have the reflective film 6 be connected to the TFT 3.

Next, a method for manufacturing the semi-transmissive-type liquidcrystal display device of the fifth embodiment is explained in order ofstep by referring to FIGS. 28A to 28D to FIGS. 29A and 29B. FIGS. 28A to28D and FIGS. 29A and 29B are cross-sectional views of thesemi-transmissive-type liquid crystal display device of FIG. 22 takenalong a line E-E.

First, as shown in FIG. 28A, after a gate line 1 (not shown), a gateelectrode 1 a, a common storage line 4 (not shown), and an auxiliarycapacitive electrode 4 a (not shown) have been formed on a transparentinsulating substrate 8 made of glass or a like by approximately the samemethod as employed in the first to fourth embodiments, a semiconductorlayer 3 a is formed with a gate insulating film 9 being interposedbetween the semiconductor layer 3 a and the gate electrode 1 a. Next, adata line 2 (not shown), a drain electrode 2 a, the source electrode 2b, and a capacitive accumulating electrode 2 c (not shown) are formed toconstruct the TFT 3 and then the passivation film 10 is formed.

Then, as shown in FIG. 28B, after the passivation film 10 has beencoated with a photosensitive acrylic resin, an acrylic resin is removedfrom the first contact hole 7, the second contact hole, a G-D convertingsection placed outside of the pixel region PX and a terminal region, anda concave/convex shaped film 11 is formed in a reflective region PXb andtransmissive region PXa containing the TFT 3. In this case, in order tosuppress attenuation of transmitted light caused by the concave/convexfilm 11, it is preferable that exposure processing is performed on allthe surfaces thereof and decoloring of the acrylic film is made.

Then, as shown in FIG. 28C, by removing the passivation film 10 placedbelow the second contact hole 7B using a resist pattern formed on theconcave/convex shaped film 11 as a mask, only the source electrode 2 bis made exposed. At this point, unlike in the case of the fourthembodiment, the passivation film 10 in the G-D converting portion and inthe terminal portion and the gate insulating film 9 are removed.

Then, as shown in FIG. 28D, after Al has been formed on all the surfacesthereof, Al in the transmissive region PXa is removed using a resistpattern as a mask and the reflective film 6 is formed on the reflectiveregion PXb. At this point, in order to prevent light from an outsidefrom entering the TFT 3, it is preferable that the reflective film 6 isformed also on the TFT 3. Furthermore, a G-D converting electrode 22 isformed using a reflective film 6. An aim of forming the G-D convertingelectrode 22 using the reflective film 6 unlike in the case of thefourth embodiment is to suppress degradation of characteristics of a TFTarray caused by plasma damage occurring at the time of sputtering usedto form the second passivation film 24 made of SiO, or a like, bydropping a potential of the TFT array, data line, or a like to a groundlevel and by forming a shunt-transistor using the G-D convertingelectrode 22.

Next, as shown in FIG. 29A, after an insulating film made of SiO, hasbeen deposited on all the surfaces thereof by using a plasma CVD methodor a like, a resist pattern is formed on the insulating film to form thesecond passivation film 24. Next, selective etching is performed on thesecond passivation film 24 below the first contact hole 7 and the secondpassivation film 24 in the terminal portion. Then, selective etching isalso performed on the passivation film 10 in the terminal portion andthe gate insulating film 9 to have the first source electrode 2 b beexposed and, at a same time, a contact hole is formed in the G-Dconverting portion and in the terminal portion. Moreover, a removingprocess to be performed on the passivation film 10 in the terminalportion and on the gate insulating film 9 and a removing process to beperformed on the passivation film 10 below the second contact hole 7Bshown in FIG. 28C may be simultaneously performed.

Then, as shown in FIG. 29B, after a transparent conductive film made ofITO has been deposited on all the surfaces thereof by using a sputteringmethod, the transparent electrode film 5, G-D converting electrode 22,and terminal electrode 23 are simultaneously formed by using a resistpattern as a mask in a manner so as to cover all surfaces of pixels.

Then, an orientated film 29 made of polyimide is formed on the activematrix substrate 12 to complete the formation of the active matrixsubstrate 12. Next, a facing substrate 16 is prepared which includes acolor filter 14, black matrix (not shown), facing electrode 15,orientated film 29 having been formed sequentially on the transparentinsulating substrate 13. Then, by inserting a liquid crystal layer 17between the active matrix substrate 12 and the facing substrate 16 andby placing phase difference plates 20 a and 20 b and polarizers 19 a and19 b on both sides of the active matrix substrate 12 and facingsubstrate 16 respectively and by placing the backlight source 18 on arear of the polarizer 19 a placed on a side of the active matrixsubstrate 12, the semi-transmissive-type liquid crystal display deviceof the embodiment as shown in FIG. 23 and FIG. 24 is manufactured.

Moreover, in the embodiment, an example is explained in which thetransparent electrode film 5 is formed above the reflective film 6 withthe second passivation film 24 being interposed between the transparentelectrode film 5 and the reflective film 6. However, if the secondpassivation film is not employed, there is a fear that contactresistance between the reflective film 6 and the transparent electrodefilm 5 becomes high and even in such the case, by employing theconfigurations employed in the embodiment, a fluctuation in a potentialof the reflective film 6 can be suppressed.

Thus, according to the semi-transmissive-type liquid crystal displaydevice of the fifth embodiment and the method for manufacturing thesame, in order to prevent a fluctuation of a potential of the reflectivefilm 6, since, by using the contact hole 7 formed in the secondpassivation film 24, each of the reflective film 6 and the transparentelectrode film 5 is connected to the source electrode 2 b and each ofthe reflective film 6 and the transparent electrode film 5 is connectedto the source electrode 2 b through the first contact hole 7A and thesecond contact hole 7B formed in the second passivation film 24, afreedom of arrangement positions in each of the contact holes 7A and 7Bcan be increased. Therefore, the reflective film 6 can be connected tothe TFT 3 without lowering a reflective characteristic.

Moreover, according to the semi-transmissive-type liquid crystal displaydevice of the fifth embodiment and the method for manufacturing thesame, before the second passivation film 24 is formed, by forming theG-D converting electrode 22 using the reflective film 6, a potential ofthe TFT array, data line, or a like can be dropped to a ground potentialand, therefore, it is possible to suppress degradation ofcharacteristics of the TFT caused by plasma damage occurring at the timeof the formation of the second passivation film.

It is apparent that the present invention is not limited to the aboveembodiments but may be changed and modified without departing from thescope and spirit of the invention. For example, in the aboveembodiments, the example is shown in which a transmissive gap and areflective gap are optimized when a twisted angle is set at about 0°,about 60° and about 72°. However, the transmissive gap and reflectivegap may be optimized by setting the twisted angle at any other degree.Also, in the above embodiments, the example is shown in which, as amaterial for the reflective film, Al or a material including an Al alloyis used and, as a material for the transparent electrode film, ITO isused. However, the present invention is not limited to the combinationof Al and the material including Al alloy and/or ITO as the material forthe reflective film, that is, so long as the combination of thematerials suppresses an electric erosion reaction at the time offormation of a pattern, any combination may be employed. Also, in theabove embodiments, the example is shown in which the TFT serving as aswitching element is formed on the active matrix substrate. However, itis not necessary that the TFT is formed on a side of the active matrix.Furthermore, the relation between the reflective film and transparentelectrode film employed in the semi-transmissive-type liquid crystaldisplay device is applied not only to each pixel but also to eachsegment (sub-pixel) making up the pixel.

1. A method for manufacturing a semi-transmissive-type liquid crystaldisplay device comprising a first substrate including a plurality ofsignal electrodes being arranged in parallel to one another along afirst direction, a plurality of scanning electrodes being arranged inparallel to one another along a second direction orthogonal to saidfirst direction and a plurality of pixel regions each having a pixelelectrode being placed in a one-to-one correspondence to an intersectionbetween each of said signal electrodes and each of said scanningelectrodes; a second substrate; a liquid crystal layer inserted betweensaid first substrate and said second substrate; a backlight; source tofeed light to said liquid crystal layer; and wherein each of said pixelregions includes a reflective region having a reflective film to receiveambient light from an outside and to display in a reflective marinerwhile being in a reflective display mode, and a transmissive regionhaving a transmissive electrode film to allow light from said backlightsource to be transmitted to display in a transmissive manner at time ofoperation in a transmissive display mode, said method comprising: afirst process of forming said reflective film making up said reflectiveregion on a surface of said first substrate facing said secondsubstrate, said first substrate and said second substrate having a firstgap there between in said reflective region; and a second process offorming said transparent electrode film making up said transmissiveregion in a manner that said transparent electrode film covers part orall of said reflective film, said first substrate and said secondsubstrate having a second gap there between in said transmissive region,wherein said first gap is set to be approximately 70% of said secondgap, and wherein a twisted angle of said liquid crystal is set to about60°.
 2. The method for manufacturing a semi-transmissive-type liquidcrystal display device according to claim 1, further comprising a thirdprocess of forming an insulating film on said reflective film, whereinsaid third process occurs between said first process and said secondprocess.
 3. The method for manufacturing a semi-transmissive-type liquidcrystal display device according to claim 2, further comprising a fourthprocess of forming a contact hole to electrically connect saidreflective film and said transparent electrode film in said insulatingfilm.
 4. A method for manufacturing a semi-transmissive-type liquidcrystal display device comprising a first substrate including aplurality of signal electrodes being arranged in parallel to one anotheralong a first direction, a plurality of scanning electrodes beingarranged in parallel to one another along a second direction orthogonalto said first direction and a plurality of pixel regions each having apixel electrode being placed in a one-to-one correspondence to anintersection between each of said signal electrodes and each of saidscanning electrodes; a second substrate; a liquid crystal layer insertedbetween said first substrate and said second substrate; a backlightsource to feed light to said liquid crystal layer; and wherein each ofsaid pixel regions includes a reflective region having a reflective filmto receive ambient light from an outside and to display in a reflectivemanner while being in a reflective display mode, and a transmissiveregion having a transmissive electrode film to allow light from saidbacklight source to be transmitted to display in a transmissive mannerat time of operations in a transmissive display mode, said methodcomprising: a first process of forming said reflective film making upsaid reflective region on a surface of said first substrate facing saidsecond substrate, said first substrate and said second substrate havinga first gap there between in said reflective region; and a secondprocess of forming said transparent electrode film making up saidtransmissive region in a manner that said transparent electrode filmcovers part or all of said reflective film, said first substrate andsaid second substrate having a second gap there between in saidtransmissive region wherein said first gap is set to be approximatelyhalf of said second gap, and wherein a twisted angle of said liquidcrystal is set to about 0°.
 5. The method for manufacturing asemi-transmissive-type liquid crystal display device according to claim4, further comprising a third process of forming an insulating film onsaid reflective film, wherein said third process occurs between saidfirst process and said second process.
 6. The method for manufacturing asemi-transmissive-type liquid crystal display device according to claim5, further comprising a fourth process of forming a contact hole toelectrically connect said reflective film and said transparent electrodefilm in said insulating film.